Sponsor refactor

part of PT story https://www.pivotaltracker.com/story/show/79559336
- replaced id with osra num on sponsor index page
- added osra_num and affiliate to sponsor show page

![screenshot from 2014-09-26 19 50 24](https://cloud.githubusercontent.com/assets/7509180/4425869/1b996610-45ae-11e4-83f8-3e4981c8d10d.png)
![screenshot from 2014-09-26 19 51 00](https://cloud.githubusercontent.com/assets/7509180/4425876/22cd2872-45ae-11e4-9d7e-d5e7653f7020.png)

I chose the term affiliate :grin:  it seemed to me to be the most succinct way to describe the relationship. 
I don't mind changing this but I think it should be based on clarification from the client rather than second guessing what they need / want.
@motasem-salem are you able to enlighten us here :smile: