Can we bump the version of the cookie crate from 0.1 to 0.2?

[letharion]

I'm trying to build https://github.com/cyderize/rust-websocket.
Now that fails (see https://github.com/cyderize/rust-websocket/issues/54) because websocket wants a newer version of openssl than hyper/cookie does, which causes a conflict.

Websocket could of course require an older version of ssl, to match hyper. However, in the long run, I'm guessing that hyper will move to new version of cookie though (with already uses the newer version) sooner or later, so I'm suggesting we bump it now.

I tried to do it locally, unfortunately 3 tests failed for me then, so some work is required. If I can work out what that is, I'll put up a PR, but I'm guessing that it's above my level of knowledge.