Contribute back

This is a contribution back to source repo of `resque-metrics`. It includes hanging pull requests:
#1 #6 #7 by @technicalpickles and @mikespokefire, also this one: https://github.com/vinted/resque-metrics/pull/1

@quirkey - please consider merging this and releasing an updated gem, or would you be willing to share collaboration rights and someone else (myself) could do it for you?

It really sucks to maintain a fork instead of pushing the source repo forward. :)

This is a screenshot of how resque-metrics web-ui looks after this pull request:

![jobs](https://cloud.githubusercontent.com/assets/70706/4676339/9db1786e-55d9-11e4-8118-0728a84670cb.png)