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

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https://hg.mozilla.org/integration/gaia-central/rev/a15825c71d6b
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #16079 from cctuan/968671

Bug 968671 - Modify Makefile for camera app to migrate camera related code from applications-data.js

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https://hg.mozilla.org/integration/gaia-central/rev/7eba440a02a2
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 968671 - Modify Makefile for camera app to migrate camera related code from applications-data.js
Bumping manifests a=b2g-bump