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

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https://hg.mozilla.org/integration/gaia-central/rev/6a6c888f1aa7
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21914 from KevinGrandon/bug_1040686_homescreen_settings

Bug 1040686 - [Homescreen] Remove column settings section

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https://hg.mozilla.org/integration/gaia-central/rev/3c732e2c334a
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1040686 - [Homescreen] Add build time configuration for settings option r=arthurcc
Bumping manifests a=b2g-bump