Rename counter_name to meter_name in alarm

In the newest ceilometer alarm version counter_name property was renamed to
meter_name. Right now heat uses old ceilometer client which still support
counter_name but newest ceilometer backend does not.

Change-Id: Ie7876119dc9b2a80d862f10de5f7265ad2a059f0
Closes-Bug: #1222830
Merge "Rename counter_name to meter_name in alarm"