Event Browser

These commits bring a simple event browser into puppetboard, similar to the event inspector in Puppet Enterprise. 

You can browse events of the latest reports grouped by nodes, containing-class or resource and get details on every event.

![eventbrowser](https://f.cloud.github.com/assets/3404133/2050011/bc26c6f8-8a6b-11e3-862e-47d909e679b8.png)