Create proper tests

[TooTallNate]

We can't really test what happens once we pass the arguments to console.log, but at least we could write tests testing the arguments that would get passed to console.log. That way we can test the debug options and make sure the formatters work, etc.

[dougwilson]

For testing in Node.js environment, you could use child_process.spawn and run a test file and logs and test the stdout from that. I was going to to that with depd, but then I couldn't get coverage information from the spawned file.

[thebigredgeek]

#370