Enable JUnit test output for deeper integration with Jenkins

We also enable XML output for coverage reports.

Change-Id: Ide5057f089f7b6271910be042b510d3b4e149a31
Signed-off-by: Peter Portante <peter.portante@redhat.com>
Reviewed-on: http://review.gluster.org/4984
Reviewed-by: Peter Portante <pportant@redhat.com>
Tested-by: Peter Portante <pportant@redhat.com>