update default_log_levels set by ceilometer

the current log levels are pretty old. update the current list to
extend current default default_log_level defined in oslo-incubator
and adding in stevedore and keystoneclient levels

Change-Id: I239645ef641613a994a48f20c0238e76dc9660f2
Partial-Bug: #1294789
Merge "update default_log_levels set by ceilometer"