Configure riak based to use multi backends
Configure riak based to use multi backends

- eleveldb will be used as regular storage
- bitcask with expiry set to 120, will be used for riak based locks

openstack/solar,pigmej/solar,openstack/solar,Mirantis/solar,Mirantis/solar,Mirantis/solar,Mirantis/solar,openstack/solar,pigmej/solar,pigmej/solar