Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
It doesn't have to be hot. In the simplest, most obvious use of it, yes it would be hot, as it results in subscribing from the top down, rather than bottom up. But it can be done lazily such as in this manner: https://github.com/benjchristensen/StreamProcessor/blob/master/src/main/java/example/Test.java#L35

```java
Publisher<String> p = getPublisher().process(new MapProcessor<Long, String>(l -> "Num: " + l));
```

And yes, you're correct, since it can choose to be either unicast or multicast it can have multiple `Subcriber`s if it wishes. I was thinking of a `Processor` as something doing transformations (like `Operator` in Rx) but it can also behave in a multicast manner (like a `Subject` in Rx).

> In my opinion, what happens to that connection after subscribers have canceled their subscription should be left to the implementation of the publisher. 

Agreed, this permits implementations such as `refCount`.

Seems like it makes sense to delete this line and just let item 4.1 cover the rules.