[1.8.x] Removed obsolete reference to media directory.

Backport of 787dd6519a from master

tests/staticfiles_tests/apps/test/static/test/file.txt

@@ -1 +1 @@
-In app media directory.
+In static directory.

tests/staticfiles_tests/test_liveserver.py

@@ -95,4 +95,4 @@ class StaticLiveServerView(LiveServerBase):
         to discover app's static assets without having to collectstatic first.
         """
         f = self.urlopen('/static/test/file.txt')
-        self.assertEqual(f.read().rstrip(b'\r\n'), b'In app media directory.')
+        self.assertEqual(f.read().rstrip(b'\r\n'), b'In static directory.')