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

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https://hg.mozilla.org/integration/gaia-central/rev/f67ed69cb1af
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #20822 from KevinGrandon/bug_1016227_collection_image

Bug 1016227 - [Collection] Update icon when apps or background changes

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https://hg.mozilla.org/integration/gaia-central/rev/55ab0509da79
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1016227 - [Collection] Update icon when apps or background changes r=daleharvey
Bumping manifests a=b2g-bump