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

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https://hg.mozilla.org/integration/gaia-central/rev/a79ef3ff2c30
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Merge pull request #19684 from justindarc/bug988651

Bug 988651 - [Camera] New sound needed for self-timer countdown

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https://hg.mozilla.org/integration/gaia-central/rev/b88d71bb58f8
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Bug 988651 - [Camera] New sound needed for self-timer countdown
Bumping manifests a=b2g-bump