Content update: script for Firefox

I made a few small changes to my script. This bash (Linux) script checks for updates to the 'arkenfox' user.js, my user-overrides.js, and also checks the last updated dates of my Firefox configuration guides.

The intention of this script is to automatically check for updates rather than running the 'arkenfox' updater script manually, plus it checks other stuff as mentioned.

The script can be download here and changes are here, however those already running the script will be notified automatically of the update.