Bundled varnish support

This pull request add's bundled varnish support to poky. When the work is 
complete, the user will be able to launch poky with varnish situated in front
to handle caching.

      |
     \|/
----------------
|  varnish  |
----------------
      |
     \|/
---------------
|   poky    |
---------------
      |
     \|/
-----------------
| postgres  |
-----------------


To do:
- [ ] add something to probe in poky
- [ ] add probes in varnish for backend (poky) health
- [ ] add wrapper script for launching both varnish and poky
- [ ] capistrano deploy


Integration testing to do:
- [ ] test POST, PUT, & DELETE purge the URL
- [ ] test proper hit
- [ ] test proper miss