Adjusting enabled/disabled services in ServicesProposal

- bnc#887688
- sshd service is adjusted by Yast Network but the service state
  is not exported to AutoYast later and also not handled
  in AutoYast import - this is a task for ServicesManager
Added test case for the new functionality
Changes, version, build info
Merge pull request #218 from kobliha/export-import-sshd

Adjusting enabled/disabled services in ServicesProposal