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

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https://hg.mozilla.org/integration/gaia-central/rev/613b95012e02
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #16783 from vingtetun/bug978546

Bug 978546 - Do not dispatch touch events to the current app while dragg...

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https://hg.mozilla.org/integration/gaia-central/rev/7af15c7e4156
Author: Vivien Nicolas <21@vingtetun.org>
Desc: Bug 978546 - Do not dispatch touch events to the current app while dragging the utility-tray. r=etienne
Bumping manifests a=b2g-bump