合并JWL,WZY,TRM代码

Change-Id: Ifb4fcad3c06733e1e005e7d8d9403e3561010fb4
diff --git a/Merge/back_wzy/extensions.py b/Merge/back_wzy/extensions.py
new file mode 100644
index 0000000..3563787
--- /dev/null
+++ b/Merge/back_wzy/extensions.py
@@ -0,0 +1,6 @@
+# extensions.py(根目录,同级于 app.py)
+from flask_sqlalchemy import SQLAlchemy
+from flask_migrate    import Migrate
+
+db      = SQLAlchemy()
+migrate = Migrate()