css: extracting font specifications of wingolf layout into one single file.

This way, the font should be easier to adjust.

Trello: https://trello.com/c/5k6dOXFA/600-font-schaltstelle-einrichten
UserVoice: https://wingolf.uservoice.com/forums/237354-allgemein/suggestions/5637826-schriftart
css: making the font slightly larger.
security fix for CVE-2014-0130.

trello: https://trello.com/c/0TcN1TSF/602-security-cve-2014-0130.

further reference: https://groups.google.com/forum/\#\!topic/rubyonrails-security/NkKc7vTW70o
updating devise due to security issue '2014-05-07 CSRF TOKEN FIXATION ATTACKS'.