Right column and layout fixes

Due to the nature of these changes, commits are bulky, so here is a proper recap:

- [new] Right hand column that allows us to stack multiple elements on the right
- [new] Social widget is on the top right and bottom of article
- [new] `cf` class is prefixed: `u-cf` (the `u` stands for "Utility"). Makes it easier to search in the codebase. Kept the old notation just in case.
- [new] `clearfix`
- [new] fake table layout classes: `u-table` `u-row` `u-cell`
- [fixed] forms styles are no longer in the head css (moved to global)
- [fixed] Most read expandable are in the main column in videos and galleries (instead of going full width)
- [removed] Unused utility classes like `pull-right`, `margin-bottom`…
- [removed] Card module applying a min-height on the article body

![ ](http://s1.developerslife.ru/public/images/gifs/4c4fb467-ed22-4c69-b85a-fcaea7426703.gif)