Error handling / logging

A bunch of things going on here:

* Faraday middleware to facilitate logging of all requests/responses sent to the adapter
* Ability to capture errors that may occur on deployment creation and bubble them back up to the local agent
* Suppression of adapter errors that occur during `deployments#show` and `deployments#destroy`
* Global error handler for general error handling

[finishes #82690376]
Yeah, makes testing things like global `:before` filters and error handlers a lot easier.

http://www.relishapp.com/rspec/rspec-rails/docs/controller-specs/anonymous-controller