Correct unit test bug in rmr-python

With RMR 1.8.x connections are forced to be asynch by default to
prevent kubernetes blocking the attempt for minutes. However, the
asynch nature of connections makes unit tests concerned with the
ability to send and receive messages non-deterministic as some
connections are established before the first message is sent, and
others are not.

This change ensures that unit tests establish connections in a
synchronous manner which ensures that the first send will not be
rejected by NNG due to a pending connection.

Signed-off-by: E. Scott Daniels <daniels@research.att.com>
Change-Id: Ic72c48480d68e0aa8ba1bc0110b6222c3707ceaa