Add autorefresh_list experiment

This experiment/feature checks at regular intervals whether there are
updates to thread lists, and notifies the user via a snackbar when
an update exists.

Bug: #42
Change-Id: I98e4aa03a7080c6bff781ce7c850477433090957
diff --git a/src/common/common.js b/src/common/common.js
index 619d6d8..f897837 100644
--- a/src/common/common.js
+++ b/src/common/common.js
@@ -82,6 +82,10 @@
     defaultValue: false,
     context: 'experiments',
   },
+  'autorefreshlist': {
+    defaultValue: false,
+    context: 'experiments',
+  },
 
   // Internal options:
   'ccdarktheme_switch_enabled': {