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

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https://hg.mozilla.org/integration/gaia-central/rev/4d96cb10a7e4
Author: George <georgeiscoming@gmail.com>
Desc: Merge pull request #11180 from cctuan/master-898290

Bug 898290 - [Gallery] HD gradient image rename

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https://hg.mozilla.org/integration/gaia-central/rev/c9dbe04b6115
Author: cctuan <georgeiscoming@gmail.com>
Desc: Bug 898290 - [Gallery] HD gradient image rename

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "15b9a5231e9e1d128f1fa1f520123f9380b5b1f1", 
+    "revision": "4d96cb10a7e4a8595b62c49904d633e4a1f88ba6", 
     "repo_path": "/integration/gaia-central"
 }