Fixed #21157 -- Fixed problems with ResolverMatch

- Fixed bug in get_callable() that caused resolve() to put a string
  in ResolverMatch.func.
- Made ResolverMatch.url_name match the actual url name (or None).
- Updated tests that used the string value in ResolverMatch.func, and
  added regression tests for this bug.
- Corrected test urls whose dummy view paths caused failures (behavior
  that was previously masked by this bug).

tests/middleware/urls.py

@@ -1,7 +1,7 @@
 from django.conf.urls import url
 
 urlpatterns = [
-    url(r'^noslash$', 'view'),
-    url(r'^slash/$', 'view'),
-    url(r'^needsquoting#/$', 'view'),
+    url(r'^noslash$', 'middleware.views.empty_view'),
+    url(r'^slash/$', 'middleware.views.empty_view'),
+    url(r'^needsquoting#/$', 'middleware.views.empty_view'),
 ]