ClusterSingletonService/EOS race condition

Steps to reproduce:
1. start ODL Karaf and install bgp, netconf-connector, restconf features
2. try to reconfigure the default bgp-rib-impl instance via restconf (controller-config)
3. observe unexpected behavior:
-topology exporters are not restarted correctly (some might run, some stay closed)
-bgp-rib-impl is not initiated (the first reconfiguration attempt can work, more tries fails and the new instance is not initiated)

Looks like problem above are related to singleton-app service, probably a closing is not correct in our implementation.

2016-09-02 10:44:28,508 | INFO | entLoopGroup-8-2 | RIBImpl | 285 - org.opendaylight.bgpcep.bgp-rib-impl - 0.6.0.SNAPSHOT | RIB Singleton Service ServiceGroupIdentifier

{value=Uri [_value=example-bgp-rib]-service-group}

registered
2016-09-02 10:44:28,508 | DEBUG | entLoopGroup-8-2 | ClusterSingletonServiceGroupImpl | 162 - org.opendaylight.mdsal.singleton-dom-impl - 2.1.0.SNAPSHOT | New Instance of ClusterSingletonServiceGroup Uri [_value=example-bgp-rib]-service-group
2016-09-02 10:44:28,508 | DEBUG | entLoopGroup-8-2 | ClusterSingletonServiceGroupImpl | 162 - org.opendaylight.mdsal.singleton-dom-impl - 2.1.0.SNAPSHOT | Initialization ClusterSingletonGroup Uri [_value=example-bgp-rib]-service-group
2016-09-02 10:44:28,509 | DEBUG | entLoopGroup-8-2 | ClusterSingletonServiceGroupImpl | 162 - org.opendaylight.mdsal.singleton-dom-impl - 2.1.0.SNAPSHOT | RegisterService method call for ClusterSingletonServiceGroup Uri [_value=example-bgp-rib]-service-group
2016-09-02 10:44:28,511 | DEBUG | lt-dispatcher-27 | ClusterSingletonServiceGroupImpl | 162 - org.opendaylight.mdsal.singleton-dom-impl - 2.1.0.SNAPSHOT | Ownership change DOMEntityOwnershipChange [entity=DOMEntity [type=org.opendaylight.mdsal.ServiceEntityType, id=/(urn:opendaylight:params:xml:ns:yang:mdsal:core:general-entity?revision=2015-09-30)entity/entity[

{(urn:opendaylight:params:xml:ns:yang:mdsal:core:general-entity?revision=2015-09-30)name=Uri [_value=example-bgp-rib]-service-group}

]], state=LOCAL_OWNERSHIP_LOST_NO_OWNER [wasOwner=true, isOwner=false, hasOwner=false], inJeopardy=false] for ClusterSingletonServiceGrou Uri [_value=example-bgp-rib]-service-group
2016-09-02 10:44:28,511 | DEBUG | lt-dispatcher-27 | ClusterSingletonServiceGroupImpl | 162 - org.opendaylight.mdsal.singleton-dom-impl - 2.1.0.SNAPSHOT | LostLeadership method for service Provider Uri [_value=example-bgp-rib]-service-group
2016-09-02 10:44:28,511 | DEBUG | lt-dispatcher-27 | ClusterSingletonServiceGroupImpl | 162 - org.opendaylight.mdsal.singleton-dom-impl - 2.1.0.SNAPSHOT | Destroy service Instance Uri [_value=example-bgp-rib]-service-group is success
2016-09-02 10:44:28,611 | DEBUG | entLoopGroup-8-2 | BgpDeployerImpl | 285 - org.opendaylight.bgpcep.bgp-rib-impl - 0.6.0.SNAPSHOT | RIB instance created RIBImpl{}