Metadata persistence in HDFS and MySQL

Partially implements the issue https://github.com/telefonicaid/fiware-connectors/issues/41

100% tests passed
Manual tests passed
I understand that after last changes now we have two methods (polymorphism):

* provisionHiveTable()
* provisionHiveTable(String tableName, Map<String, String> attrs, Map<String, String> mds)

Doubts:

* Why one of them uses tableName but not the other?
* Why you need the md to create attribute column-based tables? I mean, in that case you only need the attribute names, given that the associated metadata column can be derived from the attibute name + "_md".

In addition, I will remove the FIXME in the row method (given that you have spin-off to the other method) and change TBD in the column method for "FIXME: TBD" (to match the usual `grep FIXME`).