MVP for bob walker implemented in NASM Assembler

Minimum viable product for bob walker to function in [NASM] Assembler.

Heavily inspired by Peter Michaux excellent tutorial:
http://peter.michaux.ca/articles/assembly-hello-world-for-os-x

[NASM]: http://nasm.us/
Merge pull request #13 from dcarley/assembly-bob

MVP for bob walker implemented in NASM Assembler