VE-236: Handling of wide tables in Oasis

https://wikia-inc.atlassian.net/browse/VE-236

This is a re-merge of #1325 with additional fixes as mentioned in the ticket above.

Notable differences from the previous pull request:
* Table wrapping logic has been moved entirely into JavaScript.
* The table wrapper no longer applies `overflow: auto` by default (caused floated tables to take up an entire block of horizontal space). Tables which overflow outside of the article area are now controlled by `overflow-x: hidden` on the WikiaArticle element.
* Tall tables with overflowed content now contain a floating scrollbar which always appears near the bottom of the browser window for easier scrolling.