Initial remodeling moving the Java/JRuby instructions up
More changes/fixups
Getting rid off the DevKit information for Windows

* I believe it is not needed as we are on Java?! cc: @ashbb
* At least for my windows installations I never needed it, as
  we are on Java a compiler etc. should be unnecessary and now
  with deactivated C-extensions support...
Merge pull request #697 from shoes/readme_changes_for_release

README: Initial remodeling moving the Java/JRuby instructions up