Bump dependenices

Update dependencies and fix linting issues.

Update dependencies and test on Node 6

The module didn't change. I just updated the list of dependencies to bring everything up to date, specifically lab, and changed the travis configuration so that we start testing with Node 6.

Add support for mediatypes

This is the final bit of accept header handling that was not being handled. All other functionality remains as-is, but you can now parse the accept header for media.