Return a dictionary of column family definitions for the given
    keyspace/column_family

    CLI Example:

    .. code-block:: bash

        salt '*' cassandra.column_family_definition <keyspace> <column_family>

def column_family_definition(keyspace, column_family):
    '''
    Return a dictionary of column family definitions for the given
    keyspace/column_family

    CLI Example:

    .. code-block:: bash

        salt '*' cassandra.column_family_definition <keyspace> <column_family>

    '''
    sys = _sys_mgr()

    try:
        return vars(sys.get_keyspace_column_families(keyspace)[column_family])
    except Exception:
        log.debug('Invalid Keyspace/CF combination')
        return None