Fix attribute error in adapter

On python 2.6 module unittests do not have
SkipTest attribute - it is available only on 2.7

Also delete initialization of ceilometer client,
according it broke all ostf in case if ceilometer do
not installed

Change-Id: Iefc302e4d6860b3e3ce6951902c166b197257175
Close-bug: bug/1260199