Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/e831c963f9fd
Author: cctuan <georgeiscoming@gmail.com>
Desc: Revert "Bug 950185 - [B2G] [Settings] Network type does not show user friendly options such as 2G and 3G"

This reverts commit 446944851369aa59012e996de21232800a8db1c3.
Bumping manifests a=b2g-bump