Add endpoints for starting, stopping, and restarting all
cluster services, or specific cluster services, with all service
dependencies kept in mind. So if svcA depends on svcB, restarting
svcB will also restart svcA. Similarly, stopping svcB will first
stop svcA.
Mostly code readability fixes with some renaming and comment
updates. Also fixed some log error messages in the cluster handler.
Merge pull request #71 from continuuity/feature/restart-services

Add endpoints for starting, stopping, and restarting all