[TEST] Replace execute().actionGet() with get()
[TEST] (RecoveryPercolatorTests) Don't stop the master node and always use the client of the master node
debug log of receiving a cluster state from another master could be erroneously logged

Added trace logging to MinimumMasterNodesTests.multipleNodesShutdownNonMasterNodes
Support empty properties array in mappings
closes #5887
lightweight minimum master node recovery
don't perform full recovery when minimum master nodes are not met, keep the state around and use it once elected as master
make no master lock an instance var so it can be configured
add rejoin on master gone flag, defaults to false
defaults to false since there is still work left to properly make it work
Make noMasterBlock configurable and added simple test that shows reads do execute (partially) when m_m_n isn't met
Enable `discovery.zen.rejoin_on_master_gone` setting in DiscoveryWithNetworkFailuresTests only.
Changed the default for the 'rejoin_on_master_gone' option from false to true in zen discovery.
Added AwaitFix for the FullRollingRestartTests.
If available newly elected master node should take over previous known nodes.
Fixed compile error
Do not start a recovery process if the primary shard is currently allocated on a node which is not part of the cluster state

If a source node disconnect during recover, the target node will respond by canceling the recovery. Typically the master will respond by removing the disconnected node from the cluster state, promoting another shard to become primary. This is sent it to all nodes and the target node will start recovering from the new primary. However, if the drop of a node caused the node count to go bellow min_master_node, the master will step down and will not promote shard immediately. When a new master is elected we may publish a new cluster state (who's point is to notify of a new master) which is not yet updated. This caused the node to start a recovery to a non existent node. Before we aborted the recovery without cleaning up the shard, causing subsequent correct cluster states to be ignored. We should not start the recovery process but wait for another cluster state to come in.
RoutingService background reroute task should check if node is still master when its run

It may be that between the moment the task was added to the queue the current node stepped down from being master (due to minimum_master_nodes settings).