Create "How To Develop" Page

[josephwegner]

In order to somewhat lower the barrier to entry and encourage users both to contribute and to learn how to contribute, we should add a simple "how to contribute" page.

It should be a tutorial that runs through the whole process:

1. Create a Github Account
2. Create a fork of the pullup repo
3. Clone the repo
4. Setup dev environment
5. Add some simple feature
6. Add username to configs list
7. Commit, push
8. Create pull request
9. Signup!

I'm thinking the simple feature should be something very easy, but something that we will never actually merge into the main codebase. That way multiple users can follow the same tutorial. I suggest adding a tutorial to add a back button to the posts page - just a simple javascript window.back() thing. We would never really want it, but it feels like a real feature.