Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/4e71bd171748
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #11698 from pivanov/bug-907260

Bug 907260 - [SMS] Wrong "Add Recipient" icon r=samjoch

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https://hg.mozilla.org/integration/gaia-central/rev/29ec80208b09
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 907260 - [SMS] Wrong "Add Recipient" icon

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "d41e45bc579b9dd361dad4867297733c43633d21", 
+    "revision": "4e71bd1717484d2199e9c53631edbef47131812b", 
     "repo_path": "/integration/gaia-central"
 }