Updated install root detection to support Elm

Necessary so Elm can be installed properly since Homebrew support isn't
great.

lib/utilities.sh

@@ -79,6 +79,12 @@ get_install_root() {
   local file_name="$1"
   local file_extension=$(get_extension "$file_name")
 
+  # Special cases not supported by Homebrew.
+  if [[ "$file_name" == "elm" ]]; then
+    printf "/usr/local/bin"
+    return
+  fi
+
   # Dynamically build the install path based on file extension.
   case $file_extension in
     '')