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

========

https://hg.mozilla.org/integration/gaia-central/rev/b0fd2ccbebbc
Author: Arthur Chen <crh0716@gmail.com>
Desc: Revert "Bug 983080 - Add 2.25x icons to settings app"

This reverts commit feacb6e2a6b1b36af11f246641612cccc77426e5.
Bumping manifests a=b2g-bump