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

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https://hg.mozilla.org/integration/gaia-2_0/rev/790960034867
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1046254 - [B2G][Homescreen] Unable to launch apps after moving them to the bottom row r=aus

Conflicts:
	apps/sharedtest/test/unit/elements/gaia_grid/gaia_grid_test.js
Bumping manifests a=b2g-bump