[ADD] product_contract: Create module

* Add contract functionality to `product.templates`
* Add logic to create contracts from `sale.order` that contains contract products.

product_contract/models/sale_order_line.py

@@ -0,0 +1,14 @@
+# -*- coding: utf-8 -*-
+# Copyright 2017 LasLabs Inc.
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from odoo import fields, models
+
+
+class SaleOrderLine(models.Model):
+    _inherit = 'sale.order.line'
+
+    contract_id = fields.Many2one(
+        comodel_name='account.analytic.account',
+        string='Contract'
+    )