Added context menu items for OS X

The .workflows show up as directories in Git as they technically are but double-clicking them in OS X will open them in Automator (comes with OS X) where you can edit the script.

It's done in AppleScript because it works well with automating tasks. Basically the only thing it's used for nowadays.

The pictures are just something Automator adds on save so that when you press space on the file in Finder, you can quickly see the contents of the file. Though there seems to be a bug where the script contents are rendered upside down in the screenshot. Doesn't really matter as you can just open it anyway.

The install script makes it only appear for .gma files, JSON files and/or folders (depending on which item) but the AppleScripts themselves have "just-in-case" checks.

The items appear at the bottom of the context menu. If the user has 5 or more context menu items installed then his will be moved under a single 'Services' item which will reveal all the items when you hover over it. This is just something OS X does to keep the menu clean.