CE-1162 WAM index page redesign implementation

See [CE-1162](https://wikia-inc.atlassian.net/browse/CE-1162) for mockups and redlines.

This PR contains changes in the [WAM index page](http://adamk.wikia-dev.com/WAM) and necessary changes in WAMService that will allow to present WAM scores for the new 7 verticals.

EXPLAIN and EXPLAIN PARTITION after changes in [WAMService.class.php](https://github.com/Wikia/app/blob/CE-1162-wam-update-new/includes/wikia/services/WAMService.class.php#L299-L321):

```sql
EXPLAIN SELECT  fw1.wiki_id,fw1.wam,fw1.wam_rank,fw1.hub_wam_rank,fw1.vertical_wam_rank,fw1.peak_wam_rank,fw1.peak_hub_wam_rank,fw1.peak_vertical_wam_rank,fw1.top_1k_days,fw1.top_1k_weeks,fw1.first_peak,fw1.last_peak,fw1.hub_name,fw1.vertical_id,dw.title,dw.url,fw1.wam - IFNULL(fw2.wam, 0) as wam_change,ISNULL(fw2.wam) as wam_is_new  FROM `fact_wam_scores` `fw1` left join `fact_wam_scores` `fw2` ON ((fw1.wiki_id = fw2.wiki_id) AND (fw2.time_id = FROM_UNIXTIME(1417305600))) left join `dimension_wikis` `dw` ON ((fw1.wiki_id = dw.wiki_id))  WHERE (fw1.time_id = FROM_UNIXTIME(1417392000)) AND (dw.url like '%%' OR dw.title like '%%') AND fw1.vertical_id IN ('0','1','2','3','4','5','6','7')   ORDER BY wam DESC LIMIT 20;
```
```
+----+-------------+-------+--------+---------------+---------+---------+--------------------------------+------+-----------------------------+
| id | select_type | table | type   | possible_keys | key     | key_len | ref                            | rows | Extra                       |
+----+-------------+-------+--------+---------------+---------+---------+--------------------------------+------+-----------------------------+
|  1 | SIMPLE      | fw1   | ref    | PRIMARY       | PRIMARY | 3       | const                          | 9926 | Using where; Using filesort |
|  1 | SIMPLE      | fw2   | eq_ref | PRIMARY       | PRIMARY | 7       | const,statsdb_mart.fw1.wiki_id |    1 |                             |
|  1 | SIMPLE      | dw    | eq_ref | PRIMARY       | PRIMARY | 4       | statsdb_mart.fw1.wiki_id       |    1 | Using where                 |
+----+-------------+-------+--------+---------------+---------+---------+--------------------------------+------+-----------------------------+
```

```sql
EXPLAIN PARTITIONS SELECT  fw1.wiki_id,fw1.wam,fw1.wam_rank,fw1.hub_wam_rank,fw1.vertical_wam_rank,fw1.peak_wam_rank,fw1.peak_hub_wam_rank,fw1.peak_vertical_wam_rank,fw1.top_1k_days,fw1.top_1k_weeks,fw1.first_peak,fw1.last_peak,fw1.hub_name,fw1.vertical_id,dw.title,dw.url,fw1.wam - IFNULL(fw2.wam, 0) as wam_change,ISNULL(fw2.wam) as wam_is_new  FROM `fact_wam_scores` `fw1` left join `fact_wam_scores` `fw2` ON ((fw1.wiki_id = fw2.wiki_id) AND (fw2.time_id = FROM_UNIXTIME(1417305600))) left join `dimension_wikis` `dw` ON ((fw1.wiki_id = dw.wiki_id))  WHERE (fw1.time_id = FROM_UNIXTIME(1417392000)) AND (dw.url like '%%' OR dw.title like '%%') AND fw1.vertical_id IN ('0','1','2','3','4','5','6','7')   ORDER BY wam DESC LIMIT 20;
```
```
+----+-------------+-------+------------+--------+---------------+---------+---------+--------------------------------+------+-----------------------------+
| id | select_type | table | partitions | type   | possible_keys | key     | key_len | ref                            | rows | Extra                       |
+----+-------------+-------+------------+--------+---------------+---------+---------+--------------------------------+------+-----------------------------+
|  1 | SIMPLE      | fw1   | NULL       | ref    | PRIMARY       | PRIMARY | 3       | const                          | 9926 | Using where; Using filesort |
|  1 | SIMPLE      | fw2   | NULL       | eq_ref | PRIMARY       | PRIMARY | 7       | const,statsdb_mart.fw1.wiki_id |    1 |                             |
|  1 | SIMPLE      | dw    | NULL       | eq_ref | PRIMARY       | PRIMARY | 4       | statsdb_mart.fw1.wiki_id       |    1 | Using where                 |
+----+-------------+-------+------------+--------+---------------+---------+---------+--------------------------------+------+-----------------------------+
```

Pinging @kvas-damian @Grunny @SebastianMarzjan - the PR is ready for a code review.
Why do we need empty container?
If it's only about style maybe we could use ```::before``` or ```::after``` pseudo element?