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

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https://hg.mozilla.org/integration/gaia-central/rev/407993cc2cef
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #15684 from jankeromnes/bug963539

Bug 963539 - bin/gaia-test shouldn't depend on nodejs-legacy in ubuntu  r=bkelly

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https://hg.mozilla.org/integration/gaia-central/rev/daaca88fc04a
Author: Jan Keromnes <janx@linux.com>
Desc: Bug 963539 - bin/gaia-test shouldn't depend on nodejs-legacy in ubuntu
Bumping manifests a=b2g-bump