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

========

https://hg.mozilla.org/integration/gaia-central/rev/5d28b117f96e
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 1116128 - Adding some fuzz to the vertical swipe test. r=kgrandon

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "6d459c49070f4c80bf97795e86369ab2eb765c36", 
+    "revision": "5d28b117f96ec0362b0290689bcf87321002f173", 
     "repo_path": "integration/gaia-central"
 }