don't be "installed" during autoload removal

`el-get-remove' only sets package status to "removed" after performing
the removal; this uses `el-get-update-autoloads' to save the autoloads
file, which re-adds the just removed autoloads if the package is still
"installed" state.

This commit fixes #446 by setting the package state to "required" state
before performing the removal.  What's really wanted is the *opposite*
of "required" ("unrequired" sounds awkward), but that would be a much
more complicated change.
make autoload regexp match emacs'

The previous regex was missing grouping and matched elc files as well,
better to use the same thing that the builtin emacs autoload stuff uses.