Bundled varnish support

[drsnyder]

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.

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|  varnish  |
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|   poky    |
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| postgres  |
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To do:

• [x] add something to probe in poky (/status)
• [x] add probes in varnish for backend (poky) health
• [x] offset the key-value api with /kv/:bucket/:key. this will enable /status support
• [x] add wrapper script for launching both varnish and poky
• [x] capistrano deploy
• [x] add fall through route for anything other than /kv or /status
• [ ] update modified_at on set*
• [x] add modified_at to the HTTP header for GET

Integration testing to do:

• [x] test POST, PUT, & DELETE purge the URL
• [x] test proper hit
• [x] test proper miss

These last there were done interactively.