yast2-service-manager: several fixes

This update fixes the following issues with yast2-service-manager:
- bnc#846422: list missing LSB services
- add alias services for services-manager client
- replace old tests with rspec tests
- add yast clients: target_proposal, services_proposal, target_finish
- various fixes of modules' API
- fix the ruby dependency and drop clean section as it is useless.

Fixed bugs
systemctl --type=service list-unit-files doesn't show LSB wrapped ones
Selected Binaries
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