Code review comment for lp:~frankban/juju-gui/bug-1076404-growl

*** Submitted:

Growl-style notifications.

This branch introduces growl-style notifications
in the top-right corner of the window.
Implemented a notifier widget: it is a reusable
piece of code that just need a title, a message
and a timeout to display a notification. It is used
to render notification outside view containers, so
that notifications are preserved when the user changes
the current view.

A notifier is created when a notification is added,
following these rules:
- the notification is an error;
- the notification is local (it's not related to the
   delta stream).

The last point involves adding a new field "isDelta"
to the notification model, defaulting to false.
Notifications created when the delta stream arrives are
marked as "isDelta: true".

UI: new notifications appear on top, and disappear after
8 seconds. Mouse over prevents a notification to hide,
mouse click destroys a notification.

Also fixed a bug in the unit view: a callable was undefined
when trying to "retry" or "resolve" a unit.

R=thiago, matthew.scott
CC=
https://codereview.appspot.com/6851058

https://codereview.appspot.com/6851058/