Rewrite the high-level API (driver module) to use TendrilSink This depends on https://github.com/servo/tendril/pull/23. This also adds an API to parse from bytes, which is part of https://github.com/servo/html5ever/issues/18. r? @nox <!-- Reviewable:start --> [<img src="https://reviewable.io/review_button.png" height=40 alt="Review on Reviewable"/>](https://reviewable.io/reviews/servo/html5ever/188) <!-- Reviewable:end -->