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

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https://hg.mozilla.org/integration/gaia-central/rev/2f9ca68a745e
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 963014 - Remove hacks used to avoid update-checker. r=ahutusoru r=dhunt
Bumping manifests a=b2g-bump