ack parser.parse_ty change in quote_ty! (+ test)
Add RingBuf::as_slices as per collections reform v2.

See: https://github.com/rust-lang/rfcs/pull/509

Not sure if this is allowed to land before the RFC. Either way,
it's here for review.

r? @Gankro
cc: @bfops
libcollections: use `#[deriving(Copy)]`
libcore: use `#[deriving(Copy)]`
libfmt_macros: use `#[deriving(Copy)]`
libgetopts: use `#[deriving(Copy)]`
liblog: use `#[deriving(Copy)]`
librand: use `#[deriving(Copy)]`
librbml: use `#[deriving(Copy)]`
libregex: use `#[deriving(Copy)]`
librustc: use `#[deriving(Copy)]`
librustc_borrowck: use `#[deriving(Copy)]`
librustc_driver: use `#[deriving(Copy)]`
librustc_llvm: use `#[deriving(Copy)]`
librustc_trans: use `#[deriving(Copy)]`
librustc_typeck: use `#[deriving(Copy)]`
librustdoc: use `#[deriving(Copy)]`
librustrt: use `#[deriving(Copy)]`
libserialize: use `#[deriving(Copy)]`
libstd: use `#[deriving(Copy)]`