Move setting to the storage app

The setting COMMON_TEMPORARY_DIRECTORY is now
STORAGE_TEMPORARY_DIRECTORY.

Move file related utilities to the storage app.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/storage/settings.py

@@ -0,0 +1,17 @@
+from __future__ import unicode_literals
+
+import tempfile
+
+from django.utils.translation import ugettext_lazy as _
+
+from mayan.apps.smart_settings import Namespace
+
+namespace = Namespace(label=_('Storage'), name='storage')
+
+setting_temporary_directory = namespace.add_setting(
+    global_name='STORAGE_TEMPORARY_DIRECTORY', default=tempfile.gettempdir(),
+    help_text=_(
+        'Temporary directory used site wide to store thumbnails, previews '
+        'and temporary files.'
+    )
+)