Do not access settings on compat import

rest_framework/compat.py

@@ -94,11 +94,10 @@ else:
 # Django-guardian is optional. Import only if guardian is in INSTALLED_APPS
 # Fixes (#1712). We keep the try/except for the test suite.
 guardian = None
-if 'guardian' in settings.INSTALLED_APPS:
-    try:
+try:
     import guardian
     import guardian.shortcuts  # Fixes #1624
-    except ImportError:
+except ImportError:
     pass