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

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https://hg.mozilla.org/integration/gaia-central/rev/4b2e6eb12838
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #13304 from timdream/keyboard-perm-remove

Bug 915570 - Gaia Part II, remove the old 'keyboard' permission, r=rudyl

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https://hg.mozilla.org/integration/gaia-central/rev/77283ecd7cce
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 915570 - Gaia Part II, remove the old 'keyboard' permission