up2date "What's changed"

[Tyler larson]

I would really like to see a "What's Changed" sort of feature when
examining the to-be-installed packages in up2date. I'm not quite sure
how that should be best implemented, though. 

We've already got that nifty "View Advisory" button in the GUI. If all
the updates actually HAD an advisory it would be great. As is, though,
I've never actually seen an advisory on a Fedora package.

The way I see it, we'd probably want to do something like one of the
following:

* Start putting changelog-ish information in the advisory if the package
is just an update
* Add the ability to view the changelog from up2date
* Add the ability to view at least the last n entries in the changelog
from up2date.