Update for Flarum beta 8

[dsevillamartin]

Changes made:

• Modified all the JS directories accordingly
• Updated bootstrap.php to utilize new Extenders
  • Renamed to extend.php
• Removed unnecessary Listeners
• Update icons for FontAwesome 5
• Updated content modifier to use new interface
  • ConfigureWebApp is now in the Frontend extender
• Rename assets -> resources and move less & locale -> resources
  • Flarum copies assets folder in extension roots, so it was copying the HTML files that had no reason to be copied
• Updated & simplified .gitattributes & .gitignore

[luceos]

Looking great! Thanks for the hard work.