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

========

https://hg.mozilla.org/integration/gaia-central/rev/c281e8f5d24b
Author: Florin Strugariu <florin.strugariu@softvision.ro>
Desc: Merge pull request #27382 from viorelaioia/disable_test_on_mac

Bug 1102931 - Disable test_ftu_with_tour.py on mac

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https://hg.mozilla.org/integration/gaia-central/rev/1243de832896
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 1102931 - Disable test_ftu_with_tour.py on mac

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "e91cdb71d55e29bf41cca768591db64785d63801", 
+        "git_revision": "64113001308bd30ac3968f0e4179037dc84fddb1", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "3f869bcf3bbf485934de1539379d87b1cb71dcf3", 
+    "revision": "c281e8f5d24b7f7f5a5152d35662ed8a40519446", 
     "repo_path": "integration/gaia-central"
 }