CORE: updated javadoc

- Fixed many typos in our javadoc.
- Removed some unecessary lines from source like 'empty comments'.
- Removed historical and unused class ClustersManagerImplApi.
CORE, BEANS, GUI: renamed exception to fix spelling

- Renamed: ServiceUserOwnerAlredyRemovedException
  To: ServiceUserOwnerAlreadyRemvedException

- Use fixed exception in CORE and GUI
Merge pull request #159 from zlamalp/spell

CORE, BEANS, GUI: updated typos in javadoc