Added internationalisation to the Chora viewer

Chora viewer now supports internationalisation with multiple language translations available.

One of the coolest things about hacking on the Horde framework is that it gives me lots of features for free that I can use in my web applications. The latest thing I added to the Chora CVS viewer today is the internationalisation framework, so that the frontend can be translated to multiple languages.

I've added in a simple German translation to start with, but please contribute your own strings if you get the opportunity.