ISPN-3670 Any commands received before the initial topology is installed...

... should block
https://issues.jboss.org/browse/ISPN-3670

Because the initial cache topology is installed in a single phase,
it's possible to receive a StateRequestCommand from another node before
receiving the JOIN response from the coordinator and installing the initial
cache topology. As such, commands received before we have a cache topology
should block instead of being ignored.

No specific tests, sorry, but it should stop the random failures in the Map/Reduce tests (e.g. ReplicatedTwoNodesMapReduceTest).