Add ``user`` object to the mapping rules examples.

Every rule should have a local ``user`` object that is used to
produce a unique user_id of the federated user. Not all examples of the
OS-FEDERATION extension included such object.

Change-Id: Ib1a2a956cb3638402b283ad13841f48d31814240
Closes-Bug: #1312221
Merge "Add ``user`` object to the mapping rules examples."