Check the content and the length of certain input data and MySQL database and table names

Fixes issue https://github.com/telefonicaid/fiware-connectors/issues/114
Good idea. Looking to http://docs.ckan.org/en/ckan-2.2/api.html, it seems they have the following limitation in many places (dataset names, organization names, etc.).

> the name of the organization, a string between 2 and 100 characters long, containing only lowercase alphanumeric characters, - and _