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

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https://hg.mozilla.org/integration/gaia-central/rev/2283157fe557
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #12733 from robhudson/919894-unify-wording-in-settings

Bug 919894 - Unify some wording in settings -> Screen lock r=crh0716

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https://hg.mozilla.org/integration/gaia-central/rev/d6e6c13ba407
Author: Rob Hudson <chudson@mozilla.com>
Desc: Bug 919894 - Unify some wording in settings -> Screen lock