Sponsorship feature logo

The sponsorship feature logo visual fixes:

Position of the whole feature logo, smaller font size, max-height on a logo image in cAPI single and multiple components
![screen shot 2014-12-05 at 11 25 37](https://cloud.githubusercontent.com/assets/489567/5315130/6faea176-7c71-11e4-9e0e-f06998036c91.png)

Position of the whole feature logo, headers in one line (if text is not too long), border under headers on a front page
![screen shot 2014-12-05 at 11 29 14](https://cloud.githubusercontent.com/assets/489567/5315162/e9ce7954-7c71-11e4-81b7-02f8c3d22e15.png)

Position of the whole feature logo, additional border under the logo, no additional spaces on a tags page
![screen shot 2014-12-05 at 11 33 41](https://cloud.githubusercontent.com/assets/489567/5315214/8ce96d88-7c72-11e4-90f4-603adb05c1bb.png)

Smaller font size, max-height on a logo image on an article page
![screen shot 2014-12-05 at 11 36 08](https://cloud.githubusercontent.com/assets/489567/5315236/e118e5fa-7c72-11e4-8a20-5a766015c464.png)

Smaller font size on an interactive page
![screen shot 2014-12-05 at 11 36 57](https://cloud.githubusercontent.com/assets/489567/5315250/fe1bd8a6-7c72-11e4-899c-ac7f19dab9b9.png)
 
= `$gs-baseline / 2`