Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/59b5a0203768
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Merge pull request #15803 from gabrielesvelto/bug-947234-incremental-threads-v1.3

Bug 947234 - Improve SMS app launch latency

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https://hg.mozilla.org/integration/gaia-central/rev/1a37d498bb50
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 947234 - Quiet facebook-related errors that aren't really errors

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https://hg.mozilla.org/integration/gaia-central/rev/34ab93047dec
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 947234 - Render the threads incrementally
Bumping manifests a=b2g-bump