Bumping gaia.json for 4 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/3db5bedb25e0
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #13350 from jugglinmike/934486-npm-log

Bug 934486 - NPM Logging is too verbose

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https://hg.mozilla.org/integration/gaia-central/rev/47ddad236153
Author: Mike Pennisi <mike@mikepennisi.com>
Desc: Bug 934486 - NPM Logging is too verbose

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https://hg.mozilla.org/integration/gaia-central/rev/ec3081490ff2
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Merge pull request #12714 from fcampo/MMS-attachment-top-923023

Bug 923023 - [MMS] Move attachment button to top bar (r=rwaldron)

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https://hg.mozilla.org/integration/gaia-central/rev/95c24f715012
Author: Fernando Campo <fernando.campo@o2.com>
Desc: Bug 923023 - [MMS] Move attachment button to top bar