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

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https://hg.mozilla.org/integration/gaia-central/rev/f3ca2e36ffba
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #12820 from mjschranz/t917930

Bug 917930 - Change 'Enable USB storage' to 'USB storage'. r=crh0716

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https://hg.mozilla.org/integration/gaia-central/rev/eafb81946a78
Author: Matthew Schranz <schranz.m@gmail.com>
Desc: Bug 917930 - Change 'Enable USB storage' to 'USB storage'.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "a364333052b46caf75c44b1640c912ecf8163a1a", 
+    "revision": "f3ca2e36ffba28c5fbcbc99af5c359071b0406f7", 
     "repo_path": "/integration/gaia-central"
 }