Improve mock detector performance
Improve mock detector performance

Currently Mock Detector runs before and after each
test case. This patch makes it run only before and after
each test class.
While slightly reducing the reporting granularity
this significantly improves its performance and helps
with py34 gate timeouts.

Set the default recursion depth back to '2'
(was reduced in '314577' to workaraund gate timeouts).

Change-Id: I89a1678a9249bed77a38b4686ce43e2ce4d7c867

mmasaki/trove,openstack/trove,zhangg/trove,hplustree/trove,zhangg/trove,hplustree/trove,openstack/trove,mmasaki/trove,mmasaki/trove