Checksum validation

This feature adds the capability to do checksum validation for "values". Checksum can be included into the values by the DefaultDataGenerator based on a configurable value, and a reader can choose to validate the checksum of the value read, based on a configurable value.

Having this capability is useful to validate, say, the correctness of a datastore, at least in terms of corruption of the values being written.

Fixing serialization issues

Fixing serialization issues

Enhanced error message. Added detailedMessage field in error response with exception stack trace.

Merge pull request #232 from mdaxini/errormsg

Enhanced error message. Added detailedMessage field in error response with exception stack trace.

Fixed missing field - error response

Fixed missing filed that was not returned to user when an error occurs after invoking REST APIs.
Added missing exception messages were not relayed back for several REST calls.

CockroachDB Transaction Plugin enchancements

Avoiding possible connection leaks by closing connections to return them back to the connection pool in case of exceptions during read/write/creation operations.

CockroachDB Transaction Plugin enchancements

Bubbling up exceptions so they are counted towards failures

Dynamodb Transaction Plugin enchancements

Bubbling up exceptions and logging transaction cancellation reasons

Dynamodb Transaction Plugin

Reads involve simple read from the main table.
Writes involve dynamodb transaction containing writes to main table and child tables.

Release to upgrade consumed dependencies

Merge pull request #222 from arunagrawal84/oss_master

Provide keyspaceName while executing the statements

CassandraJavaClient: Provide keyspace name while executing the statements

Cassandra Java Client expects either the session to have the keyspace name or each statement to have keyspace name. We choose later to ensure that in future we can have statements from multiple keyspaces (if we wish to)