Extracted the configuration code into a module

This moves the configuration handling into a seperate library
which is suitable for testing and later dependency injection.

The xml code was rewritten to use the qt xml stream reader.
Silenced compiler warnings about unused variables
Extracted the sql access code into a module

This allows exchanging and testing the sql code later.
Wrote first test for xmlconfiguration

This mainly includes all the helpers to make the tests easy.