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

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https://hg.mozilla.org/integration/gaia-central/rev/e64186458e9c
Author: Luke Chang <lchang@mozilla.com>
Desc: Merge pull request #18734 from luke-chang/1002377_stingray_homescreen_template

Bug 1002377 - [Stingray] A template for the homescreen-stingray app, r=evelyn, r=johnhu

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https://hg.mozilla.org/integration/gaia-central/rev/243ec4ec4a0d
Author: Luke Chang <lchang@mozilla.com>
Desc: Bug 1002377 - [Stingray] A template for the homescreen-stingray app

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "64bce0f41677ce5ac6a01aac8db56208af980a6d", 
+    "revision": "e64186458e9c64b00deace803d388f255cbfc3c4", 
     "repo_path": "/integration/gaia-central"
 }