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

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https://hg.mozilla.org/integration/gaia-central/rev/4e1983599081
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Merge pull request #16258 from justindarc/bug959715

Resolved Bug 959715 - [B2G][Camera] Pinch to zoom in camera app switches...

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https://hg.mozilla.org/integration/gaia-central/rev/7d0ac1eb294f
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Resolved Bug 959715 - [B2G][Camera] Pinch to zoom in camera app switches orientation of screen

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "ce860e17b01f56f8c3a34546afde101543c7d57d", 
+    "revision": "4e1983599081c6bbc56b50b15c90f857a4de4724", 
     "repo_path": "/integration/gaia-central"
 }