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

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https://hg.mozilla.org/integration/gaia-central/rev/31bc2cfb43df
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15941 from KevinGrandon/bug_967187_rocketbar_cards_view_hide

Bug 967187 - [Rocketbar] Should hide when screen is locked r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/aa44d9e50c96
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 967187 - [Rocketbar] Should hide when screen is locked r=alive
Bumping manifests a=b2g-bump