Create a todo for contributions

[cuzbog]

I think a TODO list would be great for contributors. It would be much easier than searching in every file for bugs, typos and lack of documentation.

[cuzbog]

@cyderize Could you take a look at this? This library is awesome and I would seriously love to contribute, but I (and potential contributors) need to know what needs to be done :)

[cyderize]

I think the TODO list basically consists of:

• Improve the documentation and add more example function usages
• Add more tests and benches
• Figure what's going wrong with the Autobahn client tests
• Add some kind of shutdown method to the server (see add .shutdown() method to server #28)
• Implement permessage deflate extension

I'll try to write up a more useful TODO at some point. Thanks for the interest in the library!

[puhrez]

@cyderize is the above list still relevant?