Should have one page dedicated to explaining reasons for "no delete, no forks, no testing"

There are a lot of good reasons why people should not add personal forks or testing packages to Packagist. They are reiterated over and over again in IRC. There are known workarounds (creating VCS repositories, using satis to create new repository, installing own packagist, just being patient and waiting...) and some good cases where these things should be allowed (actual maintainer refuses to add composer.json, for instance).

All of this should be explained clearly and workarounds summarized and examples created. This is related to #109 and should very much be referenced (by way of links) from the warnings/messages that are displayed.