Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/a1c1856c9b08
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #16760 from KevinGrandon/bug_978433_disable_failing_test

Bug 977337 - Fix intermittent SIM tests

========

https://hg.mozilla.org/integration/gaia-central/rev/6367d9a0b5ac
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 977337 - Fix intermittent SIM tests r=rik
Bumping manifests a=b2g-bump