Update for changes in Rust libraries.

to_owned/to_strbuf -> to_string

Total{Eq,Ord} -> {Eq,Ord}

rand -> std::rand

Rng::gen_ascii_str -> Rng::gen_ascii_chars
Merge branch 'master' of github.com:BurntSushi/quickcheck

Conflicts:
	src/arbitrary.rs
	src/lib.rs