Added root password for mysql/mariadb and tabs for database settings

Added a root password for mysql/mariadb and fixed the hostname in the vm (needed for the mysql/mariadb role). This will hopefully makes clear that a user shouldn't create a "root" user (issue #91) :)
Also fixed the hostname for the vm because that was needed in the mysql role to change password for the root user.

Since i didn't know how to change the root password for pgsql, i added tabs for the databases. So now each database has it's own form with fields (as proposed in #81). I think the next step would be creating bundles (or extensions) for each role that can render a partial of the form and generate the playbook vars. Because the BundleController is getting too large at the moment.