Make Elasticsearch less exciting

Slow down recovery so it doesn't use 100% of iops.
Use disk aware allocator so it doesn't allocate shards to nodes that are
already mostly full.

DEPLOYMENT: you'll have to bounce all the Elasticsearch nodes for them
to pick this up but you can just run this on any one of the nodes instead:
curl -XPUT localhost:9200/_cluster/settings -d '{
    "transient" : {
    }
}'
curl -XPUT localhost:9200/_cluster/settings?pretty -d '{
    "transient": {
        "indices.recovery.max_bytes_per_sec" : "40mb",
        "indices.recovery.concurrent_streams" : "3",
        "cluster.routing.allocation.node_concurrent_recoveries" : "3",
        "cluster.routing.allocation.node_initial_primaries_recoveries" : "3",
        "cluster.routing.allocation.disk.threshold_enabled": true,
        "cluster.routing.allocation.disk.watermark.low": "0.85",
        "cluster.routing.allocation.disk.watermark.high": "0.95",
        "cluster.info.update.interval": "60s"
    },
    "persistent": {
        "indices.recovery.max_bytes_per_sec" : "40mb",
        "indices.recovery.concurrent_streams" : "3",
        "cluster.routing.allocation.node_concurrent_recoveries" : "3",
        "cluster.routing.allocation.node_initial_primaries_recoveries" : "3",
        "cluster.routing.allocation.disk.threshold_enabled": true,
        "cluster.routing.allocation.disk.watermark.low": "0.85",
        "cluster.routing.allocation.disk.watermark.high": "0.95",
        "cluster.info.update.interval": "60s"
    }
}'
Yup.  That is a lot of json.

Change-Id: I4d74bd1ffe15860968abddc2941f1bb2fbb5c78b