Implement binary (B and BS) unwraping

This is horribly undocumented, but if you e.g. do `String(new Buffer([97, 98, 99]))` you get "abc".  

`String(buffer)` does `[CharCode] -> String`, so to reverse it you need to do `String -> [CharCode]`.
Merge pull request #1 from brigand/patch-1

Implement binary (B and BS) unwraping