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

========

https://hg.mozilla.org/integration/gaia-central/rev/fa56fe935f58
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #14139 from caseyyee/bug-941615

Bug 941615 - [FTE] Update background and sub header colour

========

https://hg.mozilla.org/integration/gaia-central/rev/3add58fe150f
Author: Casey Yee <casey@caseyyee.com>
Desc: Bug 941615 - [FTE] Update background and sub header colour