Issue 61.

Pieced together from

http://dominik.honnef.co/posts/2013/03/writing_go_in_emacs/
add go-mode-autoloads.el

While autoloads files shouldn't usually be part of the package, this
makes upgrading a lot easier for people who were used to go-mode-load.el
being part of the Go distribution.

We did decide against keeping that name though, as go-mode-autoloads.el
is more idiomatic, and one wrong is better than two.
refine install instructions