Usergrid 182 properties consolidation default ug

Merges the corepersistence.properties into the usergrid-default.properties so that we don't have mutliple properties files lying around. 
The cassandra.url property, but isn't it still in use in the code? I don't see any code change that takes into account that the property name has changed (and been replaced by two separate properties (cassandra.hosts and cassandra.port).