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

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https://hg.mozilla.org/integration/gaia-central/rev/2845edfa1dd8
Author: Jim Porter <jporter@mozilla.com>
Desc: Merge pull request #21194 from jimporter/ringtones-new-default

Bug 1031430 - (2.0-visual-refresh)[Notifications and Alarms] - Add New S...

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https://hg.mozilla.org/integration/gaia-central/rev/30a21d9a2d02
Author: Jim Porter <jporter@mozilla.com>
Desc: Bug 1031430 - (2.0-visual-refresh)[Notifications and Alarms] - Add New Signature Firefox OS tone
Bumping manifests a=b2g-bump