Initial work to autorun on OSX.
Fix for #1253 - Create a script to configure auto-launch of server on startup, on mac - uses `launchd` and `launchctl` on OSX.
Remove commented codes.
Rename `setup_linux.sh` to `setup_unix.sh`.
Add comments re further improvement for the launchctl plist.
Make sure we unload the plist if user does not want to autoload the KA Lite server on login.
Merge pull request #2256 from cpauya/feature/1253-create-a-script-to-configure-auto-launch-of-server-on-startup-on-mac

Feature/1253 create a script to configure auto launch of server on startup on mac
restore video_file_sizes.json and lint to make json module not barf