Remote RPC Broker fails configuration transaction if clustering table service is not started.

Remote RPC Broker, requires runtime dependency not managed by config subsystem
which is clustered rpc routing table.

In second phase of commit - when all the verification should be done,
remote-rpc broker throws an exception if routing table is still not available (this one is activated by Felix DM), which tears down whole transaction and config subsystem and prevents logging.

This bug was present before, but was not seen, before performance fix was
applied to MD-SAL startup, which now gets initialized faster then original clustering service.

Remote RPC Broker should postpone it's operations till table is available,
not fail to start without table.

For now Remote RPC Broker is moved to separate transaction
https://git.opendaylight.org/gerrit/#/c/4698/1
to not prevent MD-SAL from starting.

Exception:
ava.lang.NullPointerException: null
at java.lang.StringBuilder.<init>(StringBuilder.java:109) ~[na:1.7.0_21]
at org.opendaylight.controller.sal.connector.remoterpc.ServerImpl.<init>(ServerImpl.java:79) ~[na:na]
at org.opendaylight.controller.config.yang.md.sal.remote.rpc.ZeroMQServerModule.createInstance(ZeroMQServerModule.java:49) ~[na:na]
at org.opendaylight.controller.config.yang.md.sal.remote.rpc.AbstractZeroMQServerModule.getInstance(AbstractZeroMQServerModule.java:107) ~[na:na]
at org.opendaylight.controller.config.manager.impl.ConfigTransactionControllerImpl.secondPhaseCommit(ConfigTransactionControllerImpl.java:381) ~[bundlefile:na]
at org.opendaylight.controller.config.manager.impl.ConfigRegistryImpl.secondPhaseCommit(ConfigRegistryImpl.java:264) [bundlefile:na]
at org.opendaylight.controller.config.manager.impl.ConfigRegistryImpl.commitConfig(ConfigRegistryImpl.java:208) [bundlefile:na]
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.7.0_21]
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) ~[na:1.7.0_21]
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:1.7.0_21]
at java.lang.reflect.Method.invoke(Method.java:601) ~[na:1.7.0_21]
at com.sun.jmx.mbeanserver.ConvertingMethod.invokeWithOpenReturn(ConvertingMethod.java:192) [na:1.7.0_21]