bug fix: Can't get sample through CeilometerHelper
bug fix: Can't get sample through CeilometerHelper

wrong parameter passing of function "query_sample"
the default parameter will be recognized as "user_id"

Change-Id: I293b130c3f709dc93cd4b1b7382ae8895a54765d
Closes-Bug: #1703297

stackforge/watcher,openstack/watcher,openstack/watcher,stackforge/watcher