Instead of tricking autoload-find-destination to do what we want, pull
out the relevant bits of code that do removal.
Using autoload-find-destination works in emacs 24.3 apparently because
of a bug: file-attributes returns a 4 integer list for time, but the
autoload function expects the old 2 integer format. In 24.2 where
file-attributes still returns 2 integers, the autoload section is
considered up to date and is not removed.
Note that the new dependencies code ensures that we have only one package
currently installing at any time, so that we don't need timer and defered
autoloads updating anymore. That simplifies the code a lot, and I think it
fixes issue #400, will check that next.
