Remove 'channel' column from dashboard

We'll add it back in the next release. But for 0.5b1 please remove the channel column from the dashboard.

![screen shot 2013-07-22 at 1 43 36 pm](https://f.cloud.github.com/assets/1521387/834569/053bd936-f2c4-11e2-86fe-463ada2d7267.png)