Return the contents of an interface script

    CLI Example:

    .. code-block:: bash

        salt '*' ip.get_interface eth0

def get_interface(iface):
    '''
    Return the contents of an interface script

    CLI Example:

    .. code-block:: bash

        salt '*' ip.get_interface eth0
    '''
    path = os.path.join(_RH_NETWORK_SCRIPT_DIR, 'ifcfg-{0}'.format(iface))
    return _read_file(path)