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

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https://hg.mozilla.org/integration/gaia-central/rev/710e14a7a9f5
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1043870 - Disable intermittent failing test, TEST-UNEXPECTED-FAIL | /builds/slave/test/gaia/apps/system/test/marionette/homescreen_navigation_test.js | Homescreen navigation > Going to the homescreen and back to a warm app
Bumping manifests a=b2g-bump