Adding endpoint for adding services to a cluster and hooking up
the cluster service to the solver to the planner for the add
services job. Also changing ClusterLayoutChange a little bit to
return which nodes were affected by a change in order to prevent
unnecessary work.
removing unused code and adding a package-info file.
clean up duplicate code and make sure cluster state is correct
in failure cases.
Merge pull request #83 from continuuity/feature/add-service-apis

Feature/add service apis