elpy-refactor-insert-changes: Add argument CHANGES

This was not passed before, which only worked because Emacs Lisp is
dynamically scoped.
Bump version strings to 0.9, somehow that got missed in the release.
Fixes to remove some compilation warnings
elpy-doc: Use symbol at point with no prefix arg.

Adding double prefix arg support introduced a bug where this would
always ask for a symbol to be entered. With this commit, the
function should default to the symbol at point with no prefix arg
as before.

Fixes #61