add cas support with a few tests
allow disabling of local logins.  In the instance where an .edu is using cas they may not want a user to be able to log in once the users credentials have been revoked in the system that feeds the CAS authentication server.  This is very optional
fix comment and remove url setting as it is not used.
Rename `move_selected` to `split_topic` in German client translations.
Fix a regression that broke pre-fill of username when sending private message
Add missing German server translation for `autoclosed_disabled`.
Fix unix socket paths in nginx upstream module

Unix socket paths only require a single forward slash according to the
HttpUpstreamModule documentation: http://wiki.nginx.org/HttpUpstreamModule
Fix typo in the German missing logo warning.
Add the sidekiq-failures gem so that we can diagnose failed jobs
Add styling to 'Generate API Key' button
Include pinned topics in category list.

- removes an (n+1) query for user data
- supports the preload store for the data to avoid a second request
- fix a bug where uncategorizes was reporting (0, 0, 0) for topics by week, month, year
More German translations for the admin dashboard.
Remove last occurrence of `liken`, which isn't a German word at all.
Fix replying in a topic that is uncategorized after allow_uncategorized_topics is set to false
FIX: Issues that didn't show up originally
FIX: Missing `()` made notifications invisible
Merge pull request #913 from chrishunt/chrishunt/style-api-button

Add styling to 'Generate API Key' button
Merge pull request #912 from chrishunt/chrishunt/fix-nginx-config

Fix unix socket paths in nginx sample config
Merge pull request #911 from netzpirat/update-german-translations

Update german translations
FIX: Don't cast ids to ints, as user results have string ids.