Add DIY Fork Development Setup

I added a DIY development setup for anyone who wanted an alternative to the Virtualbox, Vagrant, Ansible route. This is the environment I use to create my blog posts and figured others would find it useful
Oh, using `rvm` itself is fine. It can be installed globally on the system to `/usr/local`, or per user -- but the [per-user installation is recommended, and a global installation is possibly dangerous.](https://rvm.io/rvm/install#explained)

I was just suggesting using `which` to pull the path to Jekyll so it would work with a per-user installation of rvm.