Batch operations for HangFire.Monitor

It is better to post a screenshot here instead of writing about it :smile: 

![2014-05-19 15 32 15](https://cloud.githubusercontent.com/assets/1078718/3013493/4783b74c-df49-11e3-988a-e81718cd834b.png)

**TODO**

* [x] Replace current buttons with batch operations on each page.
* [x] Do not provide check boxes for "stale" jobs (whose state was changed during fetch).
* [x] Cleanup