Add a manage.py CLI (flask_script)

As it's the Flask-Migrate way to expose its commands (./manage.py db command).

In our case, it's specially useful for creating new migrations.

budget/manage.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+
+from flask.ext.script import Manager
+from flask.ext.migrate import Migrate, MigrateCommand
+
+from run import app
+from models import db
+
+migrate = Migrate(app, db)
+
+manager = Manager(app)
+manager.add_command('db', MigrateCommand)
+
+
+if __name__ == '__main__':
+    manager.run()