Framework for handling specs and proposals.

This adds the following to the Stack front page below the community middlewares section:

![image](https://f.cloud.github.com/assets/191200/876489/5613bee6-f8cd-11e2-8088-58ad8936fd92.png)
http://d.pr/i/hhKd

Individual proposals end up looking like this:

![image](https://f.cloud.github.com/assets/191200/876504/8a50fb06-f8cd-11e2-8aaa-a290b9cacd20.png)
http://d.pr/i/Vnim

This PR includes proposal 1 which we can use to further flesh out how we want to handle proposals along with 2 (Authentication) and 3 (Authorization) which are based on my gist minus the configuration stuff (firewalls and acls).

I think that this could work for now but I don't know how long it will work. The format is pretty nice (simple markdown files) but Sculpin isn't doing *any* work for us. I'm anxious to get it going, though, so I wanted to just try and get things rolling "the easy way" for now.

The front page is becoming a burden. I think that very soon we might consider a redesign. Mostly, I think that navigation can be added and start moving a bunch of the content to specific pages ( /toolbox/, /middlewares/, /specs/, etc ) instead of trying to have it all on the front page.