Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/503e799ca31f
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #21303 from awiss/signatures

Bug 847168 - [User Story] Email Signature r=jrburke

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https://hg.mozilla.org/integration/gaia-central/rev/3c8dba9ceb98
Author: Alex Wissmann <awiss@mozilla.com>
Desc: Bug 847168 - [User Story] Email Signature

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "90779632fefaf37388b38da6890d36b352fa2a85", 
+    "revision": "503e799ca31fb1160df383ac10682f5de807bc0e", 
     "repo_path": "/integration/gaia-central"
 }