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

========

https://hg.mozilla.org/integration/gaia-central/rev/ef4d3e1c1bde
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #13359 from pivanov/bug-930546

Bug 930546 - [Media] Replace Gradient Background with Solid Colour r=samjoch

========

https://hg.mozilla.org/integration/gaia-central/rev/3fd0de1b7204
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 930546 - [Media] Replace Gradient Background with Solid Colour

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "7af4d4e395165e4a3a0ed3024b1b9e8561cf06ec", 
+    "revision": "ef4d3e1c1bdef8dedbaf70ec8ea0834c59624993", 
     "repo_path": "/integration/gaia-central"
 }