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

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https://hg.mozilla.org/integration/gaia-central/rev/8e5ab4582834
Author: evelynhung <jj.evelyn@gmail.com>
Desc: Merge pull request #13024 from MBRSL/eng-mode

Bug 913385 - Add Hardware tests mode r=evelyn,zac

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https://hg.mozilla.org/integration/gaia-central/rev/7c55c55ae7f6
Author: Tom Jao <tjao@mozilla.com>
Desc: Bug 913385 - Add Hardware tests mode r=evelyn

    This patch organize old tests into API and UI parts, and add new Hardware tests.
    Also, there are some minor fixes on existing tests.
    HW tests mode provide the following tests:

    Audio loop
    Battery
    Bluetooth
    Camera
    Headphone
    LCD
    Physical keys
    Ringer
    SDCard
    Sensors
    Touch screen
    Vibrator