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

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https://hg.mozilla.org/integration/gaia-central/rev/c864b0ba96d3
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #21242 from KevinGrandon/bug_1030440_vertical_default_layout

Bug 1030440 - [Vertical Homescreen] Optimize default icon configuration

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https://hg.mozilla.org/integration/gaia-central/rev/70f6b31499b8
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1030440 - [Vertical Homescreen] Optimize default icon configuration r=crdlc
Bumping manifests a=b2g-bump