Simpler source dev env bootstrap script

When the tutorial suggested

    $ sudo pip install paramiko PyYAML Jinja2 httplib2

And

    $ source ./hacking/env-setup

I thought

1. I'm a py dev, I don't want that in my system python
2. I use long-lived shells, I don't want to hose my shell

So I wrote a higher level dev wrapper. I'm just starting to learn ansible, and I wrote this all on my phone in spare moments, so I'm certain something is lacking. Please let me know, and I'll button it up.