Added version release notes.

Was originally removed in this commit (a895090ca9) and has been
restored in order to handle situations where we have only a single file
install.

For example, the MacOS Config project needs this function in order to
properly install the Pathogem (Vim) file.

.ruby-version

@@ -1 +1 @@
-2.6.0
+2.6.3

CHANGES.md

@@ -1,3 +1,23 @@
+# 7.2.0 (2019-08-01)
+
+- Added file install function.
+
+# 7.1.2 (2019-06-01)
+
+- Updated contributing documentation.
+- Updated to Git Cop 3.5.0.
+
+# 7.1.1 (2019-05-01)
+
+- Added project icon to README.
+- Updated to Ruby 2.6.3.
+
+# 7.1.0 (2019-04-01)
+
+- Added XCode installer fix to troubleshooting section.
+- Updated to Ruby 2.6.1.
+- Updated to Ruby 2.6.2.
+
 # 7.0.0 (2019-01-01)
 
 - Fixed Circle CI cache for Ruby version.

CONTRIBUTING.md

@@ -1,22 +1,22 @@
 # Contributing
 
 Thanks for taking an interest in this open source project. Your support and involvement is greatly
-appreciated. The following sections detail what you need to know in order to contribute.
+appreciated. The following details what you need to know in order to contribute.
 
 ## Code
 
 1. Read the project README before starting.
-1. Fork the `master` branch of this repository and clone the fork locally.
-1. Ensure there are no setup, usage, and/or test issues.
+1. Fork and clone the `master` branch of this repository locally.
+1. Ensure there are no local setup, usage, and/or test issues.
 1. Add tests for new functionality and ensure they pass.
-1. Submit a pull request, follow the instructions it provides, and ensure the build passes.
+1. Submit a pull request, follow the instructions provided, and ensure the build passes.
 
 ## Issues
 
-- Submit an issue via the GitHub Issues tab (assuming one does not
-  already exist) and follow the instructions it provides.
+- Submit an issue via the GitHub Issues tab (assuming one does not already exist) and follow the
+  instructions provided.
 
 ## Feedback
 
 - Expect a response within one to three business days.
-- Changes, alternatives, and/or improvements might be suggested upon review.
+- Changes, alternatives, and/or improvements may be suggested upon review.

Gemfile

@@ -3,4 +3,4 @@
 source "https://rubygems.org"
 
 gem "rake", "~> 12.0"
-gem "git-cop", "~> 3.0"
+gem "git-cop", "~> 3.5"

README.md

@@ -1,3 +1,7 @@
+<p align="center">
+  <img src="mac_os.png" alt="MacOS Icon"/>
+</p>
+
 # macOS
 
 [![Circle CI Status](https://circleci.com/gh/bkuhlmann/mac_os.svg?style=svg)](https://circleci.com/gh/bkuhlmann/mac_os)
@@ -72,7 +76,7 @@ Current Version (stable):
 
     git clone https://github.com/bkuhlmann/mac_os.git
     cd mac_os
-    git checkout 7.0.0
+    git checkout 7.2.0
 
 Master Version (unstable):
 
@@ -179,13 +183,20 @@ project is built upon the functions found in the `lib` folder. See the
 
 ## Troubleshooting
 
-When using the boot disk, you might experience a situation where you see a black screen with a white
-circle and diagonal line running through it. This means macOS lost or can't find the boot disk for
-some reason. To correct this, shut down and boot up the system again while holding down the
-`OPTION+COMMAND+R+P` keys simultaneously. You might want to wait for the system boot sound to happen
-a few times before releasing the keys. This will clear the system NVRAM/PRAM. At this point you can
-shut down and restart the system following the boot disk instructions (the boot disk will be
-recognized now).
+- When using the boot disk, you might experience a situation where you see a black screen with a
+  white circle and diagonal line running through it. This means macOS lost or can't find the boot
+  disk for some reason. To correct this, shut down and boot up the system again while holding down
+  the `OPTION+COMMAND+R+P` keys simultaneously. You might want to wait for the system boot sound to
+  happen a few times before releasing the keys. This will clear the system NVRAM/PRAM. At this point
+  you can shut down and restart the system following the boot disk instructions (the boot disk will
+  be recognized now).
+- Sometimes, when installing XCode development tools (i.e. the `t` option), not all of the macOS
+  headers will be installed. This can cause issues with compiling and building native packages. For
+  example: `fatal error: 'stdio.h' file not found`. This can happen due to an intermittent bug with
+  the XCode installer. To fix this, you'll need to install this package:
+  `/Library/Developer/CommandLineTools/Packages/macOS_SDK_headers_for_macOS_10.14.pkg`. Depending on
+  your system, the version might differ, so look for a `*.pkg` in the
+  `/Library/Developer/CommandLineTools/Packages` folder.
 
 ## Versioning
 

lib/installers.sh

@@ -123,7 +123,6 @@ install_program() {
   local install_path=$(get_install_path "$program_name")
 
   if [[ ! -e "$install_path" ]]; then
-    printf "Installing: $install_path...\n"
     download_file "$url" "$program_name"
     mv "$MAC_OS_WORK_PATH/$program_name" "$install_path"
     chmod 755 "$install_path"
@@ -172,6 +171,23 @@ install_git_project() {
 }
 export -f install_git_project
 
+# Installs a single file.
+# Parameters: $1 (required) - URL, $2 (required) - Install path.
+install_file() {
+  local file_url="$1"
+  local file_name=$(get_file_name "$1")
+  local install_path="$2"
+
+  if [[ ! -e "$install_path" ]]; then
+    download_file "$file_url" "$file_name"
+    mkdir -p $(dirname "$install_path")
+    mv "$MAC_OS_WORK_PATH/$file_name" "$install_path"
+    printf "Installed: $file_name.\n"
+    verify_path "$install_path"
+  fi
+}
+export -f install_file
+
 # Downloads remote file to local disk.
 # Parameters: $1 (required) - URL, $2 (required) - File name, $3 (optional) - HTTP header.
 download_file() {