Code changes to allow compilation on rust 0.13(pre).

(Working as of Oct-30-14, at rust commit 2d27bfa)

Changed atomics to atomic
Changed StrAsciiExt to AsciiExt
Renamed fail! to panic!
Added AsRefReader and AsRefWriter traits to allow use of by_ref on Reader and Writer.
Maybe other stuff.
Merge pull request #31 from flubba86/master

Code changes to allow compilation on rust 0.13(pre).