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

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https://hg.mozilla.org/integration/gaia-central/rev/29b94593fe4f
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #20325 from hobinjk/1019816-logshake

Bug 1019816 - Logshake

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https://hg.mozilla.org/integration/gaia-central/rev/e69c2ddcef50
Author: James Hobin <jhobin@mozilla.com>
Desc: Bug 1019816 - Logshake

Add a developer option to store logcat to sdcard by shaking the phone.
Bumping manifests a=b2g-bump