Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/7b8b98b2b557
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #13090 from etiennesegonzac/bug-917222-dialing-twice

Bug 917222 - Making sure we're never dialing the same number twice. r=rik

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https://hg.mozilla.org/integration/gaia-central/rev/dc0d21d0b8ba
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 917222 - Making sure we're never dialing the same number twice.
r=rik

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https://hg.mozilla.org/integration/gaia-central/rev/4bc5d43f27c4
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #13045 from pivanov/bug-929921

Bug 929921 - [Settings-Passcode] Screen Update

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https://hg.mozilla.org/integration/gaia-central/rev/918886225cbc
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 929921 - [Settings-Passcode] Screen Update