fix restarting of services on gossipping-only members

When a node is started with -Dcassandra.join_ring=false, it is possible to talk to it via CQL. If we disable it via "nodetool disablebinary", it is not possible to enable it back with "nodetool enablebinary".

The reason why is that enablebinary command eventually calls "StorageService#checkServiceAllowedToStart" and it throws when:

1) the node is draining (which does not happen)
2) it is shutting down (which does not happen)
3) is not in NORMAL state - which happens.

The state of the gossipping-only member is STARTING for ever.

The check should make an exception here, like if it is in STARTING but -Dcassandra.join_ring=false, start it anyway.