Upgrade to Rails 4

* fixed most deprecation warnings/errors
* removed turbo-sprocks-rails3 gem
* removed yui compressor in favor of re-using sass
use mongoid from git/master
fix const issue
update for ActiveRecord changes
fixed lazy-eval in test
cleanup unused/duplicate assets
use font-awesome-rails gem which plays nicer with rails4
updated precompile patterns
create non-digest versions of files
added deprecation warning notes
ignore dev-assets