Start with German translation

Copied bg_BG translation to begin with the German (de_DE) translation
(I'm from Switzerland, so there will be country-specific «mistakes»).
Merge branch 'hotfix-0.1.2.1'
Updates to German language file
Completed first draft of German translation

There might be «errors» due Swiss/German differences.
Merge pull request #35 from scherii/master

Added German translation
Merge commit 'e35e235' into dev