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

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https://hg.mozilla.org/integration/gaia-central/rev/5aca6284801d
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #12800 from gaye/bump-marionette-apps

Bump marionette-apps to ~0.3.1 r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/c26bdfdef8e9
Author: Gareth Aye <gaye@mozilla.com>
Desc: Bump marionette-apps to ~0.3.1

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "d19c27fb6208dd425adb27d59dc276bd961ab69a", 
+    "revision": "5aca6284801d641163b675c9b4517a4ff43fdcf7", 
     "repo_path": "/integration/gaia-central"
 }