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

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https://hg.mozilla.org/integration/gaia-1_4/rev/7badd50e645a
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 1034279 - USSD messages not displayed if user leaves Dialer while sending r=etienne

I took the opportunity to re-enable a unit test

(cherry picked from commit 46bad9d7f31cbc79a4551b011529156ba8f1f8c7)

Conflicts:
	apps/communications/dialer/test/unit/mmi_ui_test.js

Signed-off-by: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Bumping manifests a=b2g-bump