Apply limit for Stats/Session queries after final merge.
Apply limit for Stats/Session queries after final merge.

For Stats/Session queries, limit was applied at each chunk
but wasn't applied after the final merge, hence final results
may contain more results than the limit specified.

Change-Id: Ie6e2f0d7d3b7f0000a4e68d454d00cbc599fb7f1
Closes-bug: #1724180

rombie/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,nischalsheth/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller,eonpatapon/contrail-controller,eonpatapon/contrail-controller,rombie/contrail-controller,rombie/contrail-controller,nischalsheth/contrail-controller,rombie/contrail-controller