IMPL: A1 <-> XApp Message Flow Testing

IMPL: A1 <-> XApp Message Flow Testing

This change adds support for testing RMR message flow between the A1 mediator
and XApps.  It consists of two major components:

o An XApp which receives policy updates from A1
o A Robot Framework testsuite to send policy requests to A1

This change also cleans up the ric_robot_suite subdirectory somewhat as part
of an ongoing process of improving robot usability.

Signed-off-by: dave kormann    <dk3239@att.com>
Change-Id: I589e9202ab277924ac848f912a01ee718cb17e14