ISPN-3670 & ISPN-3448

ISPN-3670 Any commands received before the initial topology is installed should block
https://issues.jboss.org/browse/ISPN-3670

Make StateProviderImpl block when it receives a StateRequestCommand before
it installed the initial topology.
Also, when a rebalance request is received before the join response, we
shouldn't block the joiner thread (relevant only with awaitInitialTransfer
disabled).
5642f0e

ISPN-3448 Tests from org.infinispan.distribution.rehash package fail randomly
https://issues.jboss.org/browse/ISPN-3448

* NonTxStateTransferOverwritingValue2Test should block rebalance
  confirmations to avoid the retry of the user's put command.
* NonTxJoinerBecomingBackupOwnerTest should wait until the old owners
  collect the entries to send to the backup before doing the write,
  to avoid duplicate put commands on the joiner.