Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
Why would this ever occur? The `Processor` doesn't have to request anything upstream if its downstream hasn't requested anything.

I suggest this be removed and just leave 4.1 which means that no `onNext` events will occur until after `request(n)` is called, and it is in the power of the `Processor` to call this when it wants.