Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/ad56e7047114
Author: Zibi Braniecki <zbigniew.braniecki@gmail.com>
Desc: Merge pull request #21959 from zbraniecki/1041252-update-mozl10n-api-in-system

Bug 1041252 - Update mozL10n API use cases in System. r=etienne, alive

========

https://hg.mozilla.org/integration/gaia-central/rev/3fdf4a14e1a6
Author: Zbigniew Braniecki <gandalf@mozilla.com>
Desc: Bug 1041252 - Update mozL10n API use cases in System

========

https://hg.mozilla.org/integration/gaia-central/rev/a4adb40db83f
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #22106 from etiennesegonzac/bug-1042083

Bug 1042083 - Implement App Titlebar r=alive

========

https://hg.mozilla.org/integration/gaia-central/rev/7dede7a0e8b1
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 1042083 - Implement App Titlebar
Bumping manifests a=b2g-bump