added hasOutstandingTransactions() and hasMessagesInQueue() methods
ensure Query is serializable w/ Identifiers
access to QueueManager
Updated calls to accurately check for messages.

USERGRID-1768
Merge branch 'master' into USERGRID-1768
proper query serialization
fix Query by Identifier
access to properties through ServiceManager
Merge branch 'master' into USERGRID-1768
Merge pull request #188 from apigee/USERGRID-1768

Usergrid 1768