Add ability to update with ceph-deploy

Fixes: 6146
Signed-off-by: Warren Usui <warren.usui@inktank.com>
After I moved the docstring so that both functions can use it, the HACK comment appears as a new line (green in the diff).  It was a comment that was already in the docstring (if you look at the diff you could see that it was in the previous code.

The change made should not cause new behavior.  It should not even touch the old_style upgrade method.

If you want, we could probably make that statement a little less alarming (Note that the overrides... rather than HACK: the overrides...)