Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-1_3/rev/d0584e5d9b96
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #15466 from julienw/956276-duplicate-event

Bug 956276 - [ZTE]-Two or more instances of open activity will be launch...
(cherry picked from commit 73898bf32b3da33a0de96438302feb21635285aa)

Conflicts:
	apps/system/test/unit/notifications_test.js
Bumping manifests a=b2g-bump