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

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https://hg.mozilla.org/integration/gaia-1_4/rev/7a50f7ef67fa
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1019783 - Always display IMEI codes for all SIM slots r=Rik

(cherry picked from commit c329a67bafe60032820ab64b52c07c22eeff114e)

Conflicts:
	apps/communications/dialer/test/unit/dialer_test.js
Bumping manifests a=b2g-bump