improve documentation
Using = instead of == for strict POSIX compliance.
Otherwise causes an error messages like:
remote: [: 13: 827d20eba0ac420c034b41b6c431b380c0afb560: unexpected operator
on some OSes. (Ubuntu Natty for me)
doc changes based on Eric's feedback
Merge pull request #4 from mehryar/doc_changes

Conflicts:
	README.md