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

========

https://hg.mozilla.org/integration/gaia-central/rev/b2b0a8234336
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 975233 - Reorganize the rules for installing node.js modules r=yurenju

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "c2ad1f367b62d4eca293ef42e6dba3784014c9bc", 
+    "revision": "b2b0a8234336f7004812bf27e4053957cecad492", 
     "repo_path": "/integration/gaia-central"
 }