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

========

https://hg.mozilla.org/integration/gaia-1_4/rev/b7ed6135d0b0
Author: DouglasSherk <github@sherk.me>
Desc: Bug 985888 - [DSDS] Display currently in-use SIM cards on call buttons. r=rik
Bumping manifests a=b2g-bump