Fail geohash_cell filter if geohash prefix is not enabled
closes #4335
Override DefaultExceptionHandler to filter out certain exceptions

We have the situation that some tests fail since they don't handle
EsRejectedExecutionException which gets thrown when a node shuts
down. That is ok to ignore this exception and not fail.
We also suffer from OOMs that can't create native threads but don't
get threaddumps for those failures. This patch prints the thread
stacks once we catch a OOM which can' create native threads.
Fixed incorrect results with `has_child` query with score mode if the parent type has nested object types. The inner objects (Separate Lucene docs) are also emitted as hits, which incorrectly decreased the count down short circuit mechanism in the `has_child` query.

Closes #4341
better error handling when processing refresh/update mapping
don't fail the whole bulk of updates, just the specific ones, and warn log it
Allow to disable sending a refresh-mapping to master node
When a node processed an index request, which caused it to update its own mapping, then it sends that mapping to the master. While the master process it, that node receives a state that includes an older version of the mapping. Now, there is a conflict, its not bad (i.e. the cluster state will eventually have the correct mapping), but we send for a refresh just in case form that node to the master.

With a system that has extreme cases of updates and frequent mapping changes, it might make sense to disable this feature. The indices.cluster.send_refresh_mapping setting can be introduced to support that (note, this setting need to be set on the data nodes)

Note, sending refresh mapping is more important when the reverse happens, and for some reason, the mapping in the master is ahead, or in conflict, with the actual parsing of it in the actual node the index exists on. In this case, the refresh mapping will result in warning being logged on the master node.

closes #4342
test fix
test fix