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

========

https://hg.mozilla.org/integration/gaia-central/rev/a4ef800576e5
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #14704 from KevinGrandon/bug_826274_annoying_sound

Bug 826274 - Disabled lock screen sound still plays r=timdream

========

https://hg.mozilla.org/integration/gaia-central/rev/221a6c457f11
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 826274 - Disabled lock screen sound still plays