Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/27ea1f4463f7
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Renable Python ui-tests active_sync email tests a=test-only

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https://hg.mozilla.org/integration/gaia-central/rev/1d2e4da27a6e
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Re-enable Python ui-test test_gallery_edit_photo.py a=test-only

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https://hg.mozilla.org/integration/gaia-central/rev/8f043790745c
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Re-enable Python ui-test test_mmi.py a=test-only

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https://hg.mozilla.org/integration/gaia-central/rev/ee75f135a98a
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Re-enable Python ui-test test_add_photo_to_contact.py a=test-only