Remove powermock to increase coverage

Removed powermock from the junit tests of these classes to increase
reported sonar coverage:
  RESTfulPAPEngine
  BrmsGateway

Typically added override methods to the classes under test, to replace
the overrides originally provided by powermock.

Also needed to add code to RESTfulPAPEngineTest to clear the XACML
properties before the test ran.  Modified to use the existing
XACMLProperties.reloadProperties() method.

Also modified PolicyNotificationMailTest to use a host/port that
has no listener so that the test runs faster.

Fixed some newly introduced sonar issues.

Change-Id: I65e36b01e9506987032eb21baac808ed3dfd4f47
Issue-ID: POLICY-1937
Signed-off-by: Jim Hahn <jrh3@att.com>