Bug 489941: Rework the Update Add-ons dialog (fennec update), r=gavin

mobile/app/mobile.js

@@ -151,7 +151,7 @@ pref("extensions.dss.switchPending", false);
 pref("extensions.ignoreMTimeChanges", false);
 pref("extensions.logging.enabled", false);
 pref("extensions.hideInstallButton", true);
-pref("extensions.disabledAddons.showUI", true);
+pref("extensions.showMismatchUI", false);
 
 /* these point at AMO */
 pref("extensions.update.url", "chrome://mozapps/locale/extensions/extensions.properties");