Refactor UsersController#create

* Simplify controller action
* Extract service classes
Add retry to migrate_word_counts
improve bench script
Disable ddl transactions for realz!
added international amazon domains to matcher
changed . to \.
Upgrade font-awesome to version 4
Re-apply with fixes: Stop using user agent to detect mobile devices. Use a media query and yepnope to load the appropriate css and customizations.
attempt to fix amazon item descriptions
better revision history
:scissors: scoped for Rails 4 compat
remove unused diff_engine class
Merge pull request #1729 from S-YOU/master

amazon oneboxer
Corrected the mention string in the user stream. (props to @sunyatasattva)

Previously the string would show *You mentioned {{Your Name}}*. Now it
correctly shows *You mentioned {{Other user name}}*
FIX: allow new user to post emojis
that fix should have been in the emoji plugin
FIX: images should also be inlined in the cooked view
FIX: absolute canonical link on topic pages
add image dimensions & size in lightbox
Experimental: Disqus XML importer