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

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https://hg.mozilla.org/integration/gaia-1_3/rev/460d63554ba7
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #17678 from crh0716/974253_v2_v1.3

Bug 974253 - Set preferred network type on startup based on the user preference

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https://hg.mozilla.org/integration/gaia-1_3/rev/785ed4175430
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 974253 - Set preferred network type on startup based on the user preference
Bumping manifests a=b2g-bump