Make the discussion board responsive

LEARNER-1923

common/lib/xmodule/xmodule/tabs.py

@@ -108,6 +108,13 @@ class CourseTab(object):
         """
         raise NotImplementedError()
 
+    @property
+    def uses_bootstrap(self):
+        """
+        Returns true if this tab is rendered with Bootstrap.
+        """
+        return False
+
     def get(self, key, default=None):
         """
         Akin to the get method on Python dictionary objects, gracefully returns the value associated with the