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

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https://hg.mozilla.org/integration/gaia-central/rev/fa91679addab
Author: crdlc <crdlc@tid.es>
Desc: Bug 1014966 - [Vertical Homescreen] Scrolling does not pause during divider creation r=kgrandon
Bumping manifests a=b2g-bump