Changed license to LGPLv2 + reformatted headers

- Removed "This file is part of" lines.
  This info is kind of duplicate with the top summary.
- Added a proper summary in headers.
- Reformatted all headers according to the GPL "How to apply section"

All contributors agreed about this license change
Moved the C++ part of the client to a qml plugin

TODO:
 - Test android deployment
 - Rename the "manamobile" executable to something more generic