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

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https://hg.mozilla.org/integration/gaia-central/rev/7d86aed57eca
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1002417 - [Web Components] Add simple readme for web component usage in gaia. r=drs (over irc)
Bumping manifests a=b2g-bump