Metadata persistence in HDFS and MySQL

Partially implements the issue https://github.com/telefonicaid/fiware-connectors/issues/41

100% tests passed
Manual tests passed
Why this is in "fixme" mode? I mean, the provisionHive() method should be invoked onlty for "row" mode and you can control that at sink initialization time using the proper configuration parameter. Or maybe I'm missing something... :)