Undo Hash.new workaround, add memory specs

The current workaround is broken.

A different workaround at best only passes 3/4 of the memory specs I have now added.  I don't see any benefit to adding an improved workaround when it still wont pass all specs.  So I've put the code back to the original, and when the next rubymotion build is out, these specs should pass.

Also, the CI should probably update its copy of rubymotion.