Draft release notes for the juju-core 1.9.9 release this friday

[David Cheney]

https://docs.google.com/a/canonical.com/document/d/1e9KsMbnqJN0GoQDHJ0bmfsjz1CRtC8tyH3zGI3Gtj90/edit#heading=h.h7wry0fbg197

Looking at Kanban and LP there is little to guide me for the release 
notes this week; most of the stuff looks like it occurred below the surface.

As per the previous release, these release notes will be cross posted to 
the main Juju user list.

Cheers

Dave