Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/d6aa54e33dba
Author: Jose Antonio Olivera Ortega <josea.olivera@gmail.com>
Desc: Merge pull request #13504 from jaoo/927486

Bug 927486 - [Settings] Modify Message settings category. r=arthurcc(cherry picked from commit 49b3e8cc689e1c189a86e28c20bc4726d553ee03)

Conflicts:
	apps/settings/elements/carrier_mms_settings.html
	apps/settings/index.html