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

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https://hg.mozilla.org/integration/gaia-central/rev/b18d7bedcb94
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #12588 from bebef1987/wifi_issue

Bug 922702 - Investigate test_connect_to_wifi_via_settings_app r=zac

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https://hg.mozilla.org/integration/gaia-central/rev/3dd859087021
Author: Bebe <bebe@mozilla.ro>
Desc: Bug 922702 - Investigate test_connect_to_wifi_via_settings_app

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "aeafbb7f3634b088d1f9bd6a593af6d35a118286", 
+    "revision": "b18d7bedcb94efbf84431e8f0e13826660df4a0c", 
     "repo_path": "/integration/gaia-central"
 }