add contract models and register this models admin panel

core/apps/contracts/enums/contract.py

@@ -0,0 +1,12 @@
+SIDES = (
+    ('two_or_more', 'two or more',),
+    ('customer_only', 'customer only',),
+    ('only_company', 'onlycompany'),
+)
+
+STATUS = (
+    ('created', 'created',),
+    ('signed_company', 'signed by company',),
+    ('signed_customer', 'signed by customer',),
+    ('cancelled', 'cancelled')
+)