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

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https://hg.mozilla.org/integration/gaia-central/rev/23c17f5b65cd
Author: Ben Kelly <bkelly@mozilla.com>
Desc: Merge pull request #14493 from rnowm/contacts-add-oh

Bug 947819 - [Contacts] add overflow: hidden to contcats list r=jmcf

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https://hg.mozilla.org/integration/gaia-central/rev/38f9d9acb28a
Author: rnowm <arnau@arnaumarch.com>
Desc: Bug 947819 - [Contacts] add overflow: hidden to contcats list

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "439b2b10e7879e97714f7b34e29a47f7219347db", 
+    "revision": "23c17f5b65cdf26999ed63685f842ff28f21f4e3", 
     "repo_path": "/integration/gaia-central"
 }