Better options for footer, icons display, social follow

This PR addresses #144 and #113. Adds two new `$wgForegroundFeatures` choices.

```
			'showFooterIcons' => 0,
			'addThisPUBID' => ''
```

If you enable `showFooterIcons` to `true` or `1`, then the icons for the footer will be shown instead of text. Also changes to more of the default MW layout flow when on larger displays.

If you set `addThisFollowPUBID` to your addThis publisher follow id account# and you are using the free version of horizontal follow buttons. The follow buttons will display in the footer. 

Added CSS to control the footer layout better.