Add homepage backend layout

[pixeldesu]

[!IMPORTANT] This pull request is based on #84, which should be merged first.

The layout has 4 rows:

• Hero (which is full-width in the frontend)
• Game Teaser, with a gray background, to hold the game teaser element
• The normal content section
• Another full-width section at the end for the CTA

[lkreitz]

BE configuration looks fine 👍