Adding ability to accept connections and receive messages without blocking.

[Paul-Andre]

This has to do with: https://github.com/cyderize/rust-websocket/issues/81

I added a set_nonblocking method to the Server so it is possible to make accepting connections not block, and added a set_nonblocking method to Receiver<WebSocketStream> so it is possible to make receiving messages not block.

Documentation, examples and tests still need to be written.

[illegalprime]

Thanks for the PR!
I think it would make sense to add this to the sender as well. This would be useful whenever you would only want to send the freshest data (and be on one thread): you would want to gather data, check if you can send it, if not dump it and gather new data.

I can't really do anything official here since I don't have any write permissions, but @cyderize should be around soon.

[Paul-Andre]

Ok. Do you think I should expose these methods directly from the Client?

By the way, in what situations would sending block?

[illegalprime]

Thanks for the edits again! I'm under the impression that sending would block if the TCP stream (or similar) isn't ready to be written to yet: because the OS buffer for outgoing packets is full for example.

[cyderize]

@Paul-Andre, @illegalprime this looks good to me.

If you could rebase this to squash all the commits into a single one that would be great.

Thanks for this

[illegalprime]

@Paul-Andre thanks again!