rbd: set TESTDIR when running xfstests

Signed-off-by: Sage Weil <sage@inktank.com>
ceph.conf: debug ms = 1 for monitors

Signed-off-by: Sage Weil <sage@inktank.com>
exec, pexec: set TESTDIR

Signed-off-by: Sage Weil <sage@inktank.com>
Implement timer task.
Add displaying of summary data to run.py
Merge branch 'wip-timer-wusui' of github.com:ceph/teuthology into wip-timer-wusui

Conflicts:
	teuthology/run.py
Fix run.py so summary always displays.