Add fabric and mysql-connector-python command

To install mysql-connector-python, run fabric as

    $ fab install_mysql_connector_python

It will install mysql_connector_python to the local system via `pip3` command.
Thus deployment command should call the above command via `run` like

    run('pip install fabric')
    run('fab install_mysql_connector_python')

Notice that fabric does not support Python 3 thus fabric should be
installed on Python 2 not Python 3.