respect another node running for master by temporarily not sending promises to other nodes
ensure no Prepares from the same node get queued up in the respect mechanism
Merge #151 remote-tracking branch 'refs/remotes/origin/respect-running-for-master' into origin-1.7

Conflicts:
	src/paxos/multi_paxos.ml
	src/paxos/multi_paxos_test.ml
Merge branch '1.7' of https://github.com/Incubaid/arakoon into origin-1.7

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