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

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https://hg.mozilla.org/integration/gaia-central/rev/ffe0e49fad2c
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #16494 from gaye/disable-broken-email-tests

Bug 974564 - Disable regressed email tests r=asuth

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https://hg.mozilla.org/integration/gaia-central/rev/3267861133ef
Author: Gareth Aye <gaye@mozilla.com>
Desc: Disable python persona cookies

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https://hg.mozilla.org/integration/gaia-central/rev/7343a8a2a332
Author: Gareth Aye <gaye@mozilla.com>
Desc: Disable regressed email tests r=asuth
Bumping manifests a=b2g-bump