Python 3 support, rework of the test app, german translations

These commits include:
 - German Translation
 - A rework of the test app (and real unit test for it)
 - Python 3.3 support

The rework of the test app was necessary to write function tests and make sure it's python 3 compatible.  
Keep in mind that I relied on your unit tests when adding python 3 support. If some parts of your app don't have unit tests, they might not work on python 3 as on python 2.7.

For more details, please read the commit messages.