Use new REST API to show and add included groups in WebUI

Another step to port the group related screens of the WebUI to the new
REST API.

The old RPC to add included groups was removed as it is now not used
anymore.

Change-Id: I9b364c221609a50d694e9d3fad1d3a2fa8f58f8b
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>
8 files changed