Silence urls.W002 warning.

Slashes aren't deemed necessary at start of URL patterns, but the actual check author recognized the too-strict approach for his check: https://stackoverflow.com/a/41450355

settings.py

@@ -114,6 +114,8 @@ if get_from_env('HSTS', '0') == '1':
 SECURE_BROWSER_XSS_FILTER = True
 SECURE_CONTENT_TYPE_NOSNIFF = True
 
+SILENCED_SYSTEM_CHECKS = ['urls.W002']
+
 MIDDLEWARE_CLASSES = (
     # make all things SSL
     #'sslify.middleware.SSLifyMiddleware',