[core] Fixing squid:S1319 -  Declarations should use Java collection interfaces such as "List" rather than specific implementation classes such as "LinkedList".
(manolama - updated bindings added since the PR)

Signed-off-by: Chris Larsen <clarsen@yahoo-inc.com>

This commit upgrades the Elasticsearch dependency from version 2.3.4 to
version 2.4.0.

This commit upgrades the Elasticsearch dependency from version 2.3.2 to
version 2.3.4

Today when running the Elasticsearch binding in embedded mode, a
temporary directory is used. This can be confusing for running usual
load-then-run style workflows because the temporary directory will not
be the same between runs. Instead, we should just require a directory
when running in embedded mode and this commit makes this the case.

This commit switches the Elasticsearch test runner from TestNG to JUnit.

This commit adds notes to the Elasticsearch documentation outlining the
difference between embedded and remote modes, and adds an example on
using remote mode.

This commit bumps the version of the Elasticsearch dependency for the
Elasticsearch binding to version 2.3.2.

This commit modifies the Elasticsearch client to return Status.NOT_FOUND
when an operation fails because the document requested does not
exist. This modifies the previous behavior which would return
Status.ERROR in this case.

This commit also moves the statements that would return Status.ERROR
into the corresponding catch blocks so that it is clear that
Status.ERROR is only being returned on error paths.

This commit fixes a race condition that exists between the shards being
ready to serve requests and the execution of the workload.

This commit fixes an issue with the index creation logic when the
elasticsearch.newdb flag is set to true. Namely, when running in local
mode the index would never exist (since the node always starts with a
clean temporary directory) but with elasticsearch.newdb an attempt would
be made to delete the index which would cause the workload to fail.

This commit also does a cleanup of the index creation logic using an
explicit create index request and passing the index settings along as
part of that index creation.

This commit fixes the Elasticsearch name in the README file for the
Elasticsearch project from "ElasticSearch" to "Elasticsearch".

This commit bumps the Elasticsearch dependency version from 2.1.1 to
2.2.0.

This commit fixes the Elasticsearch name throughout the YCSB benchmark
project from "ElasticSearch" to "Elasticsearch".

- define checkstyle configs in as few places as possible
- use checkstyle:check since it has defaults that match what we want (fail after logging to console)
- modules that have current failures set property checkstyle.failOnViolation to false.

Bumped elasticsearch version and fix multiple api changes.
update README.md troubleshoot section.