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

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https://hg.mozilla.org/integration/gaia-central/rev/7b8c9f45c1e5
Author: Ian Liu <iliu@mozilla.com>
Desc: Merge pull request #21987 from ian-liu/settings/bug1032071_remove_bt_panel_and_embed_it_from_bt_app

Bug 1032071 - [Settings] Remove BT panel and embed it from BT app, r=arthur, ej

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https://hg.mozilla.org/integration/gaia-central/rev/260b737c4dc7
Author: ian-liu <iliu@mozilla.com>
Desc: Bug 1032071 - [Settings] Remove BT panel and embed it from BT app

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "6b86712c03eb826f0c046f1727d7b552b1f9fed1", 
+    "revision": "7b8c9f45c1e5a53fe1725dd64c109e138289c892", 
     "repo_path": "/integration/gaia-central"
 }