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

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https://hg.mozilla.org/integration/gaia-central/rev/f1d7969e9fd8
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Merge pull request #12470 from jmcanterafonseca/email_fixed

Bug 918786 - Contacts App allows empty email addresses

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https://hg.mozilla.org/integration/gaia-central/rev/973bc5021c4a
Author: Jose M. Cantera <jmcanterafonseca@gmail.com>
Desc: Bug 918786 - Contacts App allows empty email addresses