Add missing download_url in setup.py

(transplanted from f7a0b0abea90b891003fc69c7ce7b58ddb247383)

setup.py

@@ -25,6 +25,8 @@ setup(name='trytond_stock_forecast',
     author=info.get('author', ''),
     author_email=info.get('email', ''),
     url=info.get('website', ''),
+    download_url=("http://downloads.tryton.org/" +
+        info.get('version', '0.0.1').rsplit('.', 1)[0] + '/'),
     package_dir={'trytond.modules.stock_forecast': '.'},
     packages=[
         'trytond.modules.stock_forecast',