Filters!

This pull request adds an easy way to filter events by type, count the number of events for each type, and switch from an environment to another.

[![screenshot](http://f.cl.ly/items/2A1W0D272K2a451N3W0a/Screen%20Shot%202013-02-11%20at%206.46.20%20PM.png)](http://f.cl.ly/items/2A1W0D272K2a451N3W0a/Screen%20Shot%202013-02-11%20at%206.46.20%20PM.png)