Update to serde 1.0

[KodrAus]

See the release notes.

It probably just means peppering around some lifetimes and renaming any manually implemented Visitors you might have.

I haven't found a great way to utilise the zero-copyness of serde with hyper responses because that only works when your data is contiguous and hyper will chunk response bodies.

I'm working on upgrading a couple of libraries now so will add this to my pile unless someone else wanted to pick it up :)

cc: @benashford @RoxasShadow

[benashford]

Implemented in #109 and released as 0.10.0