Improved Group Member Management on User Administration

Allows for a quick and easy group membership management on the
user-administration page. Uses the select2 UI component to
autosuggest other groups, remove existing ones and lock in automatic
groups.
FIX: NoMethodError in on extension.upcase when upload's original filename has no extension.
renamed
use computed
move available groups loader into router
move ajax into models
make jshint happy: missing semicolon
fitting images in posts without violating max width/height
FIX: count distinct badges for totals.
Merge pull request #2547 from awesomerobot/master

fitting images in posts without violating max width/height
Rename Read Faq, Read Guidelines
Add badge groupings table
FEATURE: show user what badges they have
FIX: rake admin:create suggests better name
FIX: rake admin:create ensures account active
FIX: post number is just adding noise
Emails are case insensitive
Remove hub username integration
ES6: User activity views
FEATURE: show the user's flagged/deleted posts
we can't resize images on desktop, very dangerous