Start/End event

![image](https://cloud.githubusercontent.com/assets/8709555/5211910/977b1b1c-75b9-11e4-91e6-174fd93414a4.png)

1. Can edit closed event
2. Can start event (after entering start amount)
3. Can end event (after entering end amount)

<!---
@huboard:{"order":51.1630859375,"milestone_order":11,"custom_state":""}
-->

`/events/:id/start`