CON-548: Added city_id field and index to wikia_hub_modules table

Change DB schema for MTB

Example query:

SELECT  module_id,module_status,module_data,last_edit_timestamp,last_editor_id  FROM `wikia_hub_modules`  WHERE lang_code = 'en' AND vertical_id = '2' AND hub_date = '20131209000000' AND module_id = '1';

Explain:

+----+-------------+-------------------+-------+---------------+---------+---------+-------------------------+------+-------+
| id | select_type | table             | type  | possible_keys | key     | key_len | ref                     | rows | Extra |
+----+-------------+-------------------+-------+---------------+---------+---------+-------------------------+------+-------+
|  1 | SIMPLE      | wikia_hub_modules | const | PRIMARY       | PRIMARY | 15      | const,const,const,const |    1 |       |
+----+-------------+-------------------+-------+---------------+---------+---------+-------------------------+------+-------+
1 row in set (0.00 sec)