Make letter cells on browse orgs the same width.

Before & After:

![screen shot 2014-10-27 at 1 55 05 pm](https://cloud.githubusercontent.com/assets/1044580/4797346/e6c07a76-5e0a-11e4-9b1d-ca4cc2eaeb27.png)

![screen shot 2014-10-27 at 1 54 32 pm](https://cloud.githubusercontent.com/assets/1044580/4797345/e6c05596-5e0a-11e4-84ff-dbefd78a4db6.png)