Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/bdd7c6599dd8
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #16732 from samjoch/bug-975535-vsd-refresh-update-app-icons-in-homescreen-settings-app-permissions

Bug 975535 - [VsD Refresh] Update App Icons in Homescreen & Settings/App permissions [r=ranbena,crdlc]

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https://hg.mozilla.org/integration/gaia-central/rev/4e53bd4a7793
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Bug 975535 - E.me followups [r=ranbena]

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https://hg.mozilla.org/integration/gaia-central/rev/1e3d98a27f59
Author: Sam Joch <samuel@guiora.com>
Desc: Bug 975535 - [VsD Refresh] Update App Icons in Homescreen & Settings/App Permissions
Bumping manifests a=b2g-bump