[riak] Configured RiakKVClientTest.java to work with default bucket-type instead of creating a new one.

[travis] Added riak-admin commands to create and activate test bucket.

[riak] Added RiakKVClientTest.java

[riak] Added test unit.
[riak] Set eventual consistency as default in both README.md and riak.properties file, as strong consistency it's not the main model adopted by the db (check http://docs.basho.com/riak/kv/2.1.4/developing/app-guide/strong-consistency/ for further info).
[riak] Fixed getFields() function by transforming it into createResultHashMap(). This function creates the HashMap to give as result appropriately.
[riak] Removed scan transaction support for strong consistency model. 2i search is not allowed for this model, neither there is a suitable search mean to use to achieve a proper scan transaction.
[riak] Done minor fixes to code and comments.

[riak] Done some code/comments cleanup.

[riak] Removed test unit as it only works with a local cluster installation (there is no Riak test or mock utility).
[riak] Packaged into com.yahoo.ycsb.db.riak.
[riak] Removed unused dependencies.
[riak] Bugfix for update() function that returned positive even with no nodes in the cluster.

The binding is based on the one created by Basho Technologies (available at https://github.com/basho-labs/YCSB/tree/master/riak).
[riak] Made compatible with the latest YCSB version.
[riak] Added strong consistency test support and made it default.
[riak] Added missing results return based on provided fields in scan/read functions.
[riak] Added TIME_OUT status return code for those transactions which take too long to complete.
[riak] Added flexible test parameter specification via customizable configuration file and command line options support.
[riak] Added test unit.
[riak] Removed unused Constants.java file.
[riak] Removed many unused function in the RiakUtils.java file.
[riak] Choosed to use executeAsync methods to resolve a bug that didn't allow the benchmark to end whenever one or more nodes of the cluster are killed.
[riak] Fixed license issues in all files.
[riak] Done some refinements to the code.

[elasticsearch] Elasticsearch improvements

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.

Added new binding for Riak, based on the one created by Basho Technologies (available at https://github.com/basho-labs/YCSB/tree/master/riak).

Change made to the original version:

- Made compatible with the latest YCSB version.
- Removed unused Constants.java file.
- Added strong consistency test support.
- Done some refinements to the code.
- Removed many unused function in the RiakUtils.java file.
- Choosed to use executeAsync methods to resolve a bug that didn't allow the benchmark to end whenever one or more nodes of the cluster are killed.
- Added TIME_OUT status return code.

To do:
- Add different LOG errors (i.e. insufficient_vnodes_available, ring_not_ready, etc.) - for references, check page http://docs.basho.com/riak/latest/ops/running/recovery/errors/#Errors-and-Messages
- ...

Update cassandra2-cql driver to only run tests on jdk8

[cassandra] properly clear cached containers.

clear containers before we use them rather than after, so that in the case of
exceptions we can recover.

closes #127

[S3] Close opened S3Object

[hbase10] Fix the init() method to properly construct a single…

object. Previously N objects were instantiated because the method didn't
check to see if the connection was null.

[core] Add a UnixEpochTimestampGenerator

[dynamodb] Checkstyle updates for DynamoDB.