Switch Admin Settings Lists to Select2.js

 - and use jquery.sortable to allow sorting
 - support for autocompletion
add site_setting choices

 - add site_setting choices lists to list entries
 - allows for handy autocompletion using the new select2.js UI
 - automatically merges plugin choices into existing list, allowing for easy extension
BUGFIX: Sidekiq could be initialized incorrectly in some cases

Symptom, no jobs run
remove margin-right on .contents .cooked
FIX: live reload of css
Many Plugin upgrades.
FIX: Use `replaceWith` instead of `transitionTo` when redirecting to a
user's activity. That way the back button works nicely. Also we can now
shorten a lot of links that were going to activity instead.
ES6: All components ported over
Add register_color_scheme for plugins
FIX: on mobile view, never show the show/hide preview link in composer. nexus 7 was showing it.
FIX: z-index issue with quote reply button on mobile
FIX: mobile style of edit reason input
FIX: detect css changes in plugins that use register_css
Revert "disable google, twitter, facebook logins by default"

This reverts commit d7f62f71486b7b96ac158be54bb3da631194b565.
New site setting: `limit_suggested_to_category` - ensures suggested
topics belong to the same category as the current topic and doesn't mix
in other categories.
FIX: Include `status=xyz` in queryParams
change moved post glyph
enhancing navigation
enhancing navigation
Merge pull request #2411 from awesomerobot/master

navigation enhancements