mariasql npm module support

This pull request indirectly addresses issue #578.  A new dialect 'mariadb' has been added which uses the mariasql npm module.  This module provides support for connecting to MariaDB databases, and additionally supports SSL-specific connection options.

The 'mariadb' dialect borrows heavily from the 'mysql' dialect and contains the minimum amount necessary to successfully perform queries.  Although extensive testing has not yet been performed, preliminary testing shows that it operates fine in both SSL and non-SSL modes.

Note the new ssl key within the Sequelize initialization options which is basically passed in its entirety to the mariasql module.

Thanks to iostat42 for working with me on this.