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

========

https://hg.mozilla.org/integration/gaia-central/rev/fe485e0d9007
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 923831 - Intermittent failures in test_kill_all, fix manifest syntax a=testonly r=me