reorganized code to allow inclusion without execution

[fearphage]

Reorganized code to allow module inclusion without execution. To include and register in one-shot (like before), there's a separate file for that (register.js).

If you accept this PR, you'd need to update the readme file to the following:

mocha -r mocha-http-detect/register

[fearphage]

@Chris911 Thoughts on this one?

[Chris911]

I'm just wondering if there's really a need for this. The module is really simple and I purposely kept everything in one file with a single purpose.

[fearphage]

I think it's the opposite. The number of files doesn't imply simplicity. Each file doing one simple thing makes things simple. It's more complex in a programming sense that one file does 10 things.