Add ceilometer client in devstack

Ceilometer client CLI is helpful to develop ceilometer related code. Add
it to devstack also involve more developer to use it.

Change-Id: I4147e50c00cb520ec15d63a0c34524ba8cb6654f
Signed-off-by: Yunhong, Jiang <yunhong.jiang@intel.com>
Merge "Add ceilometer client in devstack"