Update license headers and add new licenses

- Renamed LICENSE.LGPL to LICENSE.LGPLv21
- Added LICENSE.LGPLv3 & LICENSE.GPLv2
- Removed LICENSE.GPL

Change-Id: I7a8b8b787fcae9a178794364efdefe1021d10b1b
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>