Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-2_1/rev/1b248e0a631a
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1071159 - fixing statusbar visibility in fullscreen app with utility tray.

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https://hg.mozilla.org/integration/gaia-2_1/rev/0211217ad751
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 1050548 - Add high contrast recording icons

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https://hg.mozilla.org/integration/gaia-2_1/rev/493e0f5fae1d
Author: ian-liu <iliu@mozilla.com>
Desc: Bug 1057989 - [Devices][Storage] Do not auto change default media location when remove SD card without ejecting it while settings is not running in the foreground
Bumping manifests a=b2g-bump