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

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https://hg.mozilla.org/integration/gaia-central/rev/bcbed6e360b1
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #13876 from crh0716/921389

Bug 921389 - Support multi-sim for status bar r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/c004028afe54
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 921389 - Support multi-sim for status bar