Set messages ttl to claims ttl
Set messages ttl to claims ttl

Make sure messages being updated have the same ttl as claim. This update
happens when claimed messages have a ttl lower than claim's.

Implements blueprint storage-mongodb

Change-Id: Ide529895760fd6e1b207611729e1da5e250cbafb

openstack/zaqar,rackerlabs/marconi,openstack/zaqar,openstack/zaqar,openstack/zaqar