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

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https://hg.mozilla.org/integration/gaia-central/rev/6ac97ae41660
Author: Ian Liu <iliu@mozilla.com>
Desc: Merge pull request #10789 from ian-liu/bluetooth/Bug881134_hdpi/xhdpi_resolution_assets_and_layout_for_Bluetooth_File_Transfer_app

Bug 881134 - hdpi/xhdpi resolution assets and layout for Bluetooth File Transfer app, r=@rexboy7

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https://hg.mozilla.org/integration/gaia-central/rev/f04b97517eab
Author: Ian Liu <iliu@mozilla.com>
Desc: Bug 881134 - hdpi/xhdpi resolution assets and layout for Bluetooth File Transfer app