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

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https://hg.mozilla.org/integration/gaia-central/rev/2c67ef52ef14
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 932859 - Make the client provisioning PIN strings an input placeholder r=me

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "430203851f6f753adfdb109f868dfd7484208deb", 
+    "revision": "2c67ef52ef14af74020af0c555d36083ec49ec41", 
     "repo_path": "/integration/gaia-central"
 }