Handle AttributeError as well (when the imported module exists but

the specified function/class does not).

rest_framework/settings.py

@@ -171,7 +171,7 @@ def import_from_string(val, setting_name):
         module_path, class_name = '.'.join(parts[:-1]), parts[-1]
         module = importlib.import_module(module_path)
         return getattr(module, class_name)
-    except ImportError as e:
+    except (ImportError, AttributeError) as e:
         msg = "Could not import '%s' for API setting '%s'. %s: %s." % (val, setting_name, e.__class__.__name__, e)
         raise ImportError(msg)