Just use one varnish vcl template

![](http://37.media.tumblr.com/tumblr_lbo0262thm1qeejhbo1_500.jpg)
- Breaks shared code into included partials
- Switches based on machine_role
- Should mean we only have to maintain one vcl file, with a few lists (like backends etc) separated on an envrionment basis
- Started as part of [#69180058](https://www.pivotaltracker.com/story/show/69180058) but probably fixes #70928834 (https://www.pivotaltracker.com/story/show/70928834)