RFE: add Locale de_DE_du

[RainerBielefeld]

This issue is:

• Bug report
• Feature request
• Improvement

I created a locale de_DE_du from locale de_DE of wiki Version 0.3.8

The only change:
Line 52
" 'There are no Wiki pages that you have access to.' => 'Es gibt keine Wiki-Seiten, auf die Sie Zugriff haben.'," to
" 'There are no Wiki pages that you have access to.' => 'Es gibt keine Wiki-Seiten, auf die Du Zugriff hast.',"

I tested it here in an own KANBOARD installation:
Without I had English UI for wiki with enabled "German - DU" in my user profile.
After having added my "de_DE_du" Wiki UI was German

Please feel free to integrate it into the next version of Wiki plugin!