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

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https://hg.mozilla.org/integration/gaia-central/rev/224cc4ac8e7d
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #13641 from lightsofapollo/jamesisbad

Bug 937935 - fix bin/gaia-marionette +shepherd

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https://hg.mozilla.org/integration/gaia-central/rev/90523ed8a5ae
Author: James Lal <james@lightsofapollo.com>
Desc: Bug 937935 - fix bin/gaia-marionette

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "ae0b8ec678bbb782530c1151f6fd9d6f03e25ca3", 
+    "revision": "224cc4ac8e7dc6f764230d3272add6da155e6321", 
     "repo_path": "/integration/gaia-central"
 }