Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/0b8da8332338
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 942080 - Convert asynchronous activities to use promises and use the new functionality to update old notifications r=schung
Bumping manifests a=b2g-bump