Merge pull request #357 from adrianschroeter/master

- Add the OBS provides to -requires packages
- Update Summary and description for -requires meta packages
- v5.06.110 released
- Added kiwi-image:<type> -requires package provides for OBS
- v5.06.111 released
Merge pull request #358 from adrianschroeter/master

- support usage of PRODUCT_RELEASE definitions
- Fixed return value for __checkQemuImg helper in image
  format creation. The function has to return the path
  to the qemu-img binary
- v5.06.112 released
- require at least one instsource plugin via generic provide