added Transifex support

This pull request contains a few commit to make MPTagThat [Transifex](https://www.transifex.com/)-compatible.

In fact the language file format has been changed to the [Android resource xml file formt](http://help.transifex.com/features/formats.html#android-resources).

The implementation within MPTagThat to read the language files was changed as well to read the new language file format. These code changes were kept to a minimum by adding new overload methods and setting the existing ones obsolete.

A new project on Transifex.com has been created: https://www.transifex.com/projects/p/mptagthat/

This currently contains only one resource:
https://www.transifex.com/projects/p/mptagthat/resource/mptagthat/
Additional ones, like help files etc, can be added later.

The MPTagThat project is an outsourced project of the TeamMediaPortal hub project:
https://www.transifex.com/projects/p/MediaPortal/
This allows reusing the existing language teams.

Translation are currently disabled for the resources and will be enabled if MPTagThat integrates the Transifex support.