Make keyspace a config parameter and have the test suite NOT use the production keyspace.

The Cassandra keyspace was a fixed parameter. As a result the test suite would use the same keyspace as a running instance of esmond. If esmond was running the keyspace couldn't be dropped so the tests would fail. If esmond was not running the tests would pass but the production data would be lost (whoops!) These changes make the keyspace a config variable which the test suite modifies to try and avoid stomping on the production data.