AlternativeTo: Set a height for the tiles.

Fixes #728 

Old:
![screen shot 2014-05-13 at 7 55 42 pm](https://cloud.githubusercontent.com/assets/81969/2965580/1fbf6b5a-dafa-11e3-85b1-cc704e28dea7.png)

New:
![screen shot 2014-05-13 at 7 53 54 pm](https://cloud.githubusercontent.com/assets/81969/2965581/236ddf98-dafa-11e3-8735-a1a018ff66f4.png)

![screen shot 2014-05-13 at 7 53 42 pm](https://cloud.githubusercontent.com/assets/81969/2965582/266cff4e-dafa-11e3-9a8a-601fb1a10b6c.png)