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

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https://hg.mozilla.org/integration/gaia-central/rev/79e2c9d07063
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #16256 from KevinGrandon/bug_971484_system_dialercomms_v2

Bug 971484 - [System2] Instantiable DialerComms r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/51917db7e908
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 971484 - [System2] Instantiable DialerComms r=alive
Bumping manifests a=b2g-bump