Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/86a8720554f2
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 1197816 - Disable verticalhome app_packaged_fail_test.js

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https://hg.mozilla.org/integration/gaia-central/rev/d55b2973ecd7
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Bug 1236308 - Disable app_installed_test.js

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https://hg.mozilla.org/integration/gaia-central/rev/c4bcea9c9bf9
Author: Gregor Wagner <anygregor@gmail.com>
Desc: Merge pull request #33857 from gregorwagner/master

Bug 1239268 - Fix typo in system tests. r=mhenretty

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https://hg.mozilla.org/integration/gaia-central/rev/a8f754b5c9b5
Author: Gregor Wagner <anygregor@gmail.com>
Desc: Bug 1239268 - Fix typo in system tests

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "c592a10f88a4d694a6788eaf82f1fccb36e2d752", 
+        "git_revision": "bc1be88909cb74b0e19507c83d1083c9bbcb4b5a", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "3d39f954612633fba18ea70975f0e9ab9c850be3", 
+    "revision": "86a8720554f2756ce564a9fc61705ed795abf498", 
     "repo_path": "integration/gaia-central"
 }