make emacs rust-mode package.el compatible (marmalade/melpa) #3187

This would make it a lot easier to install with package.el (from marmalade and melpa at least), and automate the byte-compilation.

This should follow the "marmalade package format" as described here http://marmalade-repo.org/doc-files/package.5.html . It is quite straightforward I believe, just adding a header/footer/dependencies and mark autoloads mostly.

I will give it a try when I get back later this week, if no one has done it first.

http://marmalade-repo.org/
http://melpa.milkbox.net/