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

========

https://hg.mozilla.org/integration/gaia-central/rev/0bcb51b672d5
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #15392 from crh0716/951888

Bug 951888 - Add a check on the existence of mozMobileConnections r=alive

========

https://hg.mozilla.org/integration/gaia-central/rev/d624a804852e
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 951888 - Add a check on the existence of mozMobileConnections