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

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https://hg.mozilla.org/integration/gaia-central/rev/63d432c3395f
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #14375 from mcav/land-939375

Bug 939375 - [email] POP3: UX for when there are too many messages in the spool. r=asuth

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https://hg.mozilla.org/integration/gaia-central/rev/d78f61233a85
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Bug 939375 - [email] POP3: UX for when there are too many messages in the spool. r=asuth