Fix: Various performance bottlenecks

The way this library used 'arguments' and try/catch left it
suffering in the v8 optimizer. These changes alleviate some of the
problems.

Signed-off-by: Kevin Conway <kevinjacobconway@gmail.com>
Change: README to markdown file

The npm README viewer only support md so the rst file looks a
little strange.

Signed-off-by: Kevin Conway <kevinjacobconway@gmail.com>