v3.5.0

Changes:

• Route methods now only pass the response object to callbacks. The parsed response body for JSON responses can now be found on the response.body property and the unparsed response body can be found on the response.rawBody property. Errors passed to the callbacks have an additional error.response property that contains the response object if applicable.
• Fixed a bug where auto-creating a collection, database or graph that already exists would result in an error (see #25).
• All async functions now also return a promise, if the global ES6 Promise constructor is defined.