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

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https://hg.mozilla.org/integration/gaia-central/rev/49950f830ee6
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #12259 from lightsofapollo/gaia-ui-tests-travis

Bug 916305 - Gaia ui tests travis

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https://hg.mozilla.org/integration/gaia-central/rev/13c2ca7c1f26
Author: James Lal <james@lightsofapollo.com>
Desc: xfail test_clock_turn_on_off_alarm.py

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https://hg.mozilla.org/integration/gaia-central/rev/3a93cb8a84ef
Author: James Lal <james@lightsofapollo.com>
Desc: xfail test_settings_change_keyboard_language.py

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https://hg.mozilla.org/integration/gaia-central/rev/a2031a207635
Author: James Lal <james@lightsofapollo.com>
Desc: Bug 916305 - Gaia ui test travis setup