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

========

https://hg.mozilla.org/integration/gaia-central/rev/2761bef23995
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 969280 - disabling all navigation bar tests in dialer for tbpl bustage

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "branch": "", 
         "revision": ""
     }, 
-    "revision": "87a6dd5b96f96800288c56c9c10e1763c145a886", 
+    "revision": "2761bef239957844e6126ef252b82b5f63b304e7", 
     "repo_path": "/integration/gaia-central"
 }