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

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https://hg.mozilla.org/integration/gaia-central/rev/57413760b640
Author: Yuren Ju <yurenju@gmail.com>
Desc: Merge pull request #15149 from yurenju/multilocale-integration

Bug 900182 - integration for multilocale r=@timdream

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https://hg.mozilla.org/integration/gaia-central/rev/2424d7769009
Author: Yuren Ju <yurenju@gmail.com>
Desc: Bug 900182 - integration for multilocale