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

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https://hg.mozilla.org/integration/gaia-central/rev/2d283425987b
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #13607 from JohanLorenzo/calendar-app-object

Bug 937532 - Migrate calendar tests to use an app object

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https://hg.mozilla.org/integration/gaia-central/rev/dfbf59aca77c
Author: Johan LORENZO <johan.lorenzo@gmail.com>
Desc: Bug 937532 - Migrate calendar tests to use an app object