Use Ansible instead of a shell script to deploy the site from Jenkins.

Use it to manage the deployment and configuration of the node.js backend (#375) as well. Retargeted from #378.
Actually, apparently it's by name when you're creating the host as well as when referencing it.

```
    - name: Provision 2 production web servers
      rax:
        credentials: ~/.rackspace_cloud_credentials
        name: "prod_webserver_%01d"
        flavor: performance1-1
        image: ubuntu-1204-lts-precise-pangolin
        networks:
          - public
          - private
          - buildnet # Create or use an already existing network here
        region: "{{ lookup('env', 'RAX_REGION') | upper }}"
        state: present
        count: 2
        exact_count: yes
        group: prod_webservers
        wait: yes
        key_name: drg
      register: rax
```

Later we just grab it by `hostvars[host]['rax_networks']['buildnet'][0]`. The grab bag here though is that you don't know whether you're getting IPv4 or IPv6 (either assume or check).