add date field to decay function doc
change default number of test jvms to 1
the auto default can cause a lot of pressure on a machine when running the tests (each process actually runs a multi node cluster)
Make TestCluster based integration tests more repoducible

While testing an async system providing reproducible tests that
use randomized components is a hard task we should at least try to
reestablish the enviroment of a failing test as much as possible.
This commit allows to re-establish the shared 'TestCluster' by
resetting the cluster to a predefined shared state before each test.

Before this commit a tests that is executed in isolation was likely
using a entirely different node enviroment as the failing test since
the 'TestCluster' kept intermediate nodes started by other tests around.
Simplify NestedFieldComparators for numerics

The average and sum comparators basically share the same code which is
copy-past today. We can simplify this into a base class which reduces
code duplication and prevents copy-paste bugs.
Randomized SearchScanTests
Disable random ram directories to prevent OOM during tests.

We need to find a way to enable this without adding crazy heaps etc.
Maybe only selected tests can run this.
If there is an exception that indicates that the shard isn't available then the exception should bubble up to the TransportShardSingleOperationAction class, so the shard level request can be retried on a different shard. (multi term vector api)
Don't wrap the exception in an ElasticSearchException when shard isn't available.
If there is an exception that indicates that the shard isn't available then the exception should bubble up to the TransportShardSingleOperationAction class, so the shard level request can be retried on a different shard. (multi get api)
Added acknowledgment timeout test to OpenCloseIndexTests
Delete Template: When deleting with * and no templates exists, don't 404
closes #3723
improve logging on before/after shared cluster tests
Fix formatting of the documentation.

Remaining '@'s have been replaced with '`'s.
Removed wrong assertion from OpenCloseIndexTests

If a request hasn't been acknowledged, there's no guarantee for any node to hold the up-to-date cluster state (not even the master yet, as the execution is asynchronous)
improve failure message when timing out on green/yellow
call ensureGreen() to get more meaningful debug output on failure
GetActionTests: call ensureGreen() to get more meaningful debug output on failure
call ensureGreen instead of explicit call
escape spaces in JAVA_HOME

fix 3725
Check if nodes have been shut down in TestCluster#beforeTest

The test cluster ignored randomly teared down nodes in tests.
This commit also adds some debug logging to the TestCluster#beforeTest
method.