Remove dependency on org.powermock (PowerMockito)

Replace use of PowerMockito packages with the standard Mockito.
Create a BabelServiceClient Factory class to simplify mocking.
Remove duplicated "no mock" test classes that were not in fact free of
mocking. Add a dummy sample CSAR file for testing of artifact downloads.

Change-Id: Ib86f560e514e1efab0e2f732e494a032d555c7c3
Issue-ID: AAI-1049
Signed-off-by: mark.j.leonard <mark.j.leonard@gmail.com>