v0.11.8 - Coelacanth

While there are other sticks in the fire, both goiardi related and otherwise, here's another release with tweaks and improvements to brighten the days of anyone who happens to use goiardi.

From the CHANGELOG:

* Made some small tweaks and updates to the depsolver to make that a little
  better. NB: Down the road, there may be some further changes to the depsolver,
  especially where 'most constrained' cookbooks are concerned.
* Update the circleci config to use the version 2.0 syntax.
* Add purging old sandboxes that have been hanging around for too long.