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

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https://hg.mozilla.org/integration/gaia-central/rev/283d9d13ce49
Author: Ben Francis <ben@tola.me.uk>
Desc: Merge pull request #11667 from lightsofapollo/integration-tests-always-run-npminstall

Bug 907799 - run npm install in all cases. r=benfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/b60eee67e0d4
Author: James Lal <james@lightsofapollo.com>
Desc: Bug 907799 - run npm install in all cases.