[Merge] lp:~rodrigo-moya/system-service/new-interfaces into lp:system-service

[Rodrigo Moya]

I've just added a test program (test/interactive/test_systemd) that tests the DBus interface, and also fixed the systemd's comments. So it's now fully ready for review
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https://code.launchpad.net/~rodrigo-moya/system-service/new-interfaces/+merge/83308
Your team Ubuntu Core Development Team is requested to review the proposed merge of lp:~rodrigo-moya/system-service/new-interfaces into lp:system-service.