Features/Notification Progress Bar

Summary
Give the notifications progress bars (if they want)

Owner

 * Name: Sam P.


 * Email: samDELETEME@sugarlabs.org (You need to get rid of the DELETEME.)

Current status

 * Targeted release: 0.104
 * Last updated: 10/Aug/2014
 * Percentage of completion: 50% - needs discussion

Benefit to Sugar

 * Progress notifications
 * Background software update notifications
 * Coolness

Scope
It is a small change that does not break compatibility.

It needs Features/Notification_Replacement so your progress bar can move!

UI Design
The bar replaces the summary. Check out this video.

How To Test
Run this Gist in Pippy.

Dependencies
None!

Contingency Plan
People are sad :(

Documentation
Using the notification hints:


 * x-sugar-progress-bar must be True
 * x-sugar-progress-pulse True for a pulsing bar (see the start of the video)
 * x-sugar-progress-fraction 0.0 to 1.0 for the progress bar progress (e.g.: 0.5 is 50% filled)

Release Notes
Added notification progress bar functionality.

Comments and Discussion
https://github.com/sugarlabs/sugar/pull/393