Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/8371602fc92e
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 922647 - Disable e.me tests on Travis to save time a=testonly r=me
Bumping manifests a=b2g-bump