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

========

https://hg.mozilla.org/integration/gaia-central/rev/76d79ac7239a
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 956031 - Checking for geolocation icon precludes this test from running on CI environments r=me

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "efaae1b2b4a42e08b6c7f190fa331225350944aa", 
+    "revision": "76d79ac7239a952d957a1c730225329fd4c9f689", 
     "repo_path": "/integration/gaia-central"
 }