Automate setting up the local Ansible environment

[skyfaller]

Running these playbooks on a new computer is actually really difficult, and requires too many steps to make it practical to manually walk new sysadmins through it every time.

Fortunately, we can use Ansible prompts to ask the user to input important information such as their Linode API key, and use that to automatically set up their computer with the desired Ansible dev environment.