Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/25b78e722d95
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #16085 from timdream/build-appdata-wallpaper

Bug 968702 - Add Makefile for wallpaper app, r=yurenju

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https://hg.mozilla.org/integration/gaia-central/rev/7352b0b74147
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 968702 - Add Makefile for wallpaper app
Bumping manifests a=b2g-bump