rx-recompose: Improved API

• New module: createComponent maps a stream of owner props to a stream of React nodes.
• observeProps is now called mapPropsStream
• observeProps used to allow you to return an object of streams, which it would convert into a stream of objects. This form caused too much confusion, in my experience, so it's been removed in favor of explicit calls to combineLatest.
• createEventHandler now returns an object with stream and handler, where the handler pushes new values onto the stream. Previously, it returns a function that was both a handler and a stream. This new form is akin to mailboxes in Elm.

Refer to the README for full info.