Renamed readable_format flag to human

Closes #3541
when doing range queries within a query_string query, the range terms should only be lowercased if the field is not numeric

fixes #3540
Share shards computation logic between searchShards and searchShardsCount
Prevent FVH from entering a very long running loop on large docs with high freq phrase terms.

Terminate phrase searches early if max phrase window is exceeded in
FastVectorHighlighter to prevent very long running phrase
extraction if phrase terms are high frequent. See LUCENE-5182

Closes #3543
Add stub ClusterInfoService, DiskUsage and DiskThresholdDecider

Change AllocationDecider API to take ClusterInfoService, update all
other deciders
flesh out DiskThresholdDecider mock a bit more
start work on ClusterInfoService
more fleshing out of DiskThresholdDecider
refactor ClusterInfoService into InternalClusterInfoService and
ClusterInfoService interface so it can be injected into BalancedShardsAllocator
missing license
use ClusterInfoService instead of InternalClusterInfoService for BSA
fail-open for no node info
Switch to threaded update, still not able to get a client node properly
working transport for NodesStatsAction
ClusterInfoService works, but isn't correctly passed to BSA yet