add contract models and register this models admin panel

core/apps/contracts/enums/contract_file.py

@@ -0,0 +1,12 @@
+FILE_TYPE = (
+    ('all_files', 'all files',),
+    ('PDF', 'pdf',),
+    ('word_files', 'word files',),
+    ('image', 'image'),
+)
+
+USER_PERMISSION = (
+    ('all', 'all'),
+    ('add', 'add'),
+    ('delete', 'delete'),
+)