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

========

https://hg.mozilla.org/integration/gaia-central/rev/2a243155b608
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 922582 - Remove the caller number when entering switch-calls mode r=etienne

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "ed215858b4dab10dc92324f13a41d569d534db7d", 
+    "revision": "2a243155b608e768b3c9f8e9c73ebe61c2140dd8", 
     "repo_path": "/integration/gaia-central"
 }