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

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https://hg.mozilla.org/integration/gaia-central/rev/0d2fa4669af6
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #13798 from bebef1987/xfail_email

Bug 939771 - xfail test_setup_basic_gmail.py

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https://hg.mozilla.org/integration/gaia-central/rev/fd02cc8ddfe9
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 939771 - xfail test_setup_basic_gmail.py

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https://hg.mozilla.org/integration/gaia-central/rev/4cc02a8961cd
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #13796 from viorelaioia/bug_939720

Bug 939720 - Failure in test_ftu_skip_tour

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https://hg.mozilla.org/integration/gaia-central/rev/5bf1e7880bcc
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 939720 - Failure in test_ftu_skip_tour