Multiple url support, CLI parsing module and dynamic build

Pretty massive update.

I hope you like the build of `penthouse.js`. It retreives the values from `package.json` so that they are always in sync. No more manually updating the preamble :-) 

The CLI parsing is now done by a separate module. 

And there is also support for multiple urls. If you just pass one then it functions the same as before. But the order of the css and url had to change, so that is a breaking change.

fixes #10
This usage line can't be correct - the script now writes to files directly. Needs to be updated. Again, I can take care of this.