Prepare for 0.4.0.M1

Docs tweaking and package info renaming in README.md
@benjchristensen I agree with your reasoning and the second bullet point, that is what is under discussion in rule 18 and we should change it to your proposed text to clarify it. The first bullet point is related to #62 and should be discussed separately (i.e. keep the current 2^31-1 request limit for this PR).