Devtools Sync
Removed custom request and response middlewares #87

* Add Faraday Middleware as a dependency
* Use FaradayMiddleware's JSON Middlewares
* Use custom Error middleware based upon old Response class
* Use Faraday's Logger Middleware #87
Make the Faraday connection accessible #87

This allows the user to add request and response middleware
for example.
Merge pull request #92 from triAGENS/use-faraday-middleware

Use faraday middleware