adding markdown support for documentation.

http://rubydoc.info/gems/yard/file/docs/GettingStarted.md
https://trello.com/c/duZ2CFlD/202-dokumentation
https://trello.com/c/mt2yZ8zk/514-dokumentation-verbessern
adding some missing locales.
fixing label in reset password mechanism.
having the search field also search profile field labels.

https://trello.com/c/ZcbEerLl/520-fix-suche-soll-auch-profilfeld-labels-durchsuchen