Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/3872d43fc543
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #11671 from pivanov/bug-907680

Bug 907680 - [HD][Settings] System Update "Install Now" button should beblue not red r=samjoch

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https://hg.mozilla.org/integration/gaia-central/rev/62eee62e8976
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 907680 - [HD][Settings] System Update "Install Now" button should be blue not red