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

========

https://hg.mozilla.org/integration/gaia-central/rev/161ad4c25015
Author: b2gautomation <jonallengriffin@gmail.com>
Desc: Bug 907941 - gaia-ui-tests-pushbot (see bug)

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "118497e9bd320d65b847be7b7e70c021d4ae56f4", 
+    "revision": "161ad4c25015b074acd9d1e9257d2dd449a3faa8", 
     "repo_path": "/integration/gaia-central"
 }