Rearranged some file-related tests

Just moving around some tests to be more logically grouped.

tests/file_storage/models.py

+"""
+42. Storing files according to a custom storage system
+
+``FileField`` and its variations can take a ``storage`` argument to specify how
+and where files should be stored.
+"""
+
+import random
+import tempfile
+
+from django.db import models
+from django.core.files.storage import FileSystemStorage
+
+
+temp_storage_location = tempfile.mkdtemp()
+temp_storage = FileSystemStorage(location=temp_storage_location)
+
+class Storage(models.Model):
+    def custom_upload_to(self, filename):
+        return 'foo'
+
+    def random_upload_to(self, filename):
+        # This returns a different result each time,
+        # to make sure it only gets called once.
+        return '%s/%s' % (random.randint(100, 999), filename)
+
+    normal = models.FileField(storage=temp_storage, upload_to='tests')
+    custom = models.FileField(storage=temp_storage, upload_to=custom_upload_to)
+    random = models.FileField(storage=temp_storage, upload_to=random_upload_to)
+    default = models.FileField(storage=temp_storage, upload_to='tests', default='tests/default.txt')
+    empty = models.FileField(storage=temp_storage)

tests/files/models.py

-"""
-42. Storing files according to a custom storage system
-
-``FileField`` and its variations can take a ``storage`` argument to specify how
-and where files should be stored.
-"""
-
-import random
-import tempfile
-
-from django.db import models
-from django.core.files.storage import FileSystemStorage
-
-
-temp_storage_location = tempfile.mkdtemp()
-temp_storage = FileSystemStorage(location=temp_storage_location)
-
-class Storage(models.Model):
-    def custom_upload_to(self, filename):
-        return 'foo'
-
-    def random_upload_to(self, filename):
-        # This returns a different result each time,
-        # to make sure it only gets called once.
-        return '%s/%s' % (random.randint(100, 999), filename)
-
-    normal = models.FileField(storage=temp_storage, upload_to='tests')
-    custom = models.FileField(storage=temp_storage, upload_to=custom_upload_to)
-    random = models.FileField(storage=temp_storage, upload_to=random_upload_to)
-    default = models.FileField(storage=temp_storage, upload_to='tests', default='tests/default.txt')
-    empty = models.FileField(storage=temp_storage)