Make it easy to build and deploy

[davidbalbert]

Ideally, this means creating a Makefile that can do the following:

1. Build www_alum
2. Generate a tarsnap key
3. Generate smtpd.pem

We should also have documentation that makes it apparent how to set up a new instance of alum from scratch on your local computer. Something like:

On your development computer:

1. Install Go version X.Y.Z and ansible-playbook.
2. make tarsnap.key
3. make smtpd.pem
4. make www_alum and uncomment the www_alum role
5. Edit inventory.ini
6. ansible-playbook ...