[core, Cassandra, gemfire, mapkeeper] Fixing squid:S2864 -  "entrySet()" should be iterated when both the key and value are needed

Merge pull request #555 from DevFactory/staging/return-statements-should-not-occur-in-finally-blocks-fix-2

"return" statements should not occur in "finally" blocks

[Cassandra] removed tracing from insert

Merge pull request #565 from DevFactory/staging/Collection-isEmpty-should-be-used-to-test-for-emptiness-fix-9

Collection.isEmpty() should be used to test for emptiness

pmd:UnnecessaryConstructor - Unnecessary constructor, squid:EmptyStatementUsageCheck - Empty statements should be removed

[core dynamodb googledatastore infinispan] Fixing pmd:UnnecessaryConstructor - Unnecessary constructor, squid:EmptyStatementUsageCheck - Empty statements should be removed

[core accumulo couchbase memcached] Fixing squid:S1155 - Collection.isEmpty() should be used to test for emptiness

Unused local variables should be removed

[cassandra cassandra2 dynamodb hbase098 hbase10 jdbc s3] Fixing squid:S1481 - Unused local variables should be removed

[mongodb] Update to use BATCHED_OK Status for batched inserts.

This ensures that users do not confuse the results from batched
and non-batched operations.

Closes #522

[tarantool] Update tarantool driver version

[mongodb] Update the documentation for MongoDB. Use YCSB from binary instead

[kudu] revert kudu version to 0.6.0

blocks gh-542

[kudu] Bump the default admin timeout

The default 10s timeout can be too low when creating large tables on
slow devices. This patch just uses the already-defined default of
60s for that operation.

[cassandra] added large deprecation message

[cassandra2] added better property handling

[memcached] Removed groupId (duplicates parent).

For reference, other bindings don't appear to specify a `groupId` at this level
in their `pom.xml` files.

@shivam-maharshi says in a [comment][1]:

> The groupId here is the duplicate of the parent groupId. This is creating a
> problem in the maven build.

  [1]: https://github.com/brianfrankcooper/YCSB/commit/d4b1d247a31cf9fbf42b2e324b5b1cc27fdd9565#commitcomment-15030853

[Core] Add retry for insertion logic to make the load process more robust

Prefix the retry limit property name with core_workload.

[core] Incorporate CR Feedback

Prefix the retry limit property with "core_workload".

The default behavior is NO RETRY, which is the current behavior.

But optionally user can enable retry if they are working with a DB backend that is better tolerated by allowing a few retries.

- Remove trailing whitespaces,
- Break longlines to below 120 chars
- Right indentation.

This is to prepare for the next commit that will add retry logic to insert to make the load process more fault tolerant.

[memcached] Added memcached binding.

The memcached support was extracted from PR #98 by @jbellis, with cleanups to
bring it in line with current APIs and style guide.

This PR also addresses issue #326.

[kudu] Bump Kudu dependency to 0.6.0

This version and the previous one are wire compatible, the only code
chance reflects a naming change in the client API.

[scripts] Improve errors in bin/ycsb

* Handles missing "java" with an error message.
* Adds a check_output method for users running on Python 2.6.
* Prints an error when importing argparse fails (third party module on Python 2.6).

[build] changed checkstyle linelength to 120