Ceilometer user is needed for other ceilometer services to
authenticate with keystone even when API is not present.
So the data can be dispatched to gnocchi. Lets keep these
separate so user always exists even when api is not.
Depends-On: Iffebd40752eafb1d30b5962da8b5624fb9df7d48
Closes-bug: #1677354
Change-Id: I8f4e543a7cef5e50a35a191fe20e276d518daf20