Add ability to control route table req frequency

Add ability to control route table req frequency

This change introduces the RMR_RTREQ_FREQ environment variable
which allows the frequency that RMR will send requests to the
route manager to be externally controlled. Valid values are between
1 and 300 seconds inclusive.

This change also closes a test initialisation issue causing unit
test failures in the CI environment.

Issue-ID: RIC-630

Signed-off-by: E. Scott Daniels <daniels@research.att.com>
Change-Id: I399cca797c6b13a1b7fab0c9c17d54c419cf169f