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

========

https://hg.mozilla.org/integration/gaia-central/rev/c4289b783eb9
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1013842 - Follow-up, remove unused menu CSS r=me

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "84f413a40a6c044e3bea359b44fe2b3952180aa3", 
+    "revision": "c4289b783eb96a97df42f5ff1a614bd7c680dce5", 
     "repo_path": "/integration/gaia-central"
 }