Fix to the models problem in flask

• In the migrations/env.py import your models module
  
• Now execute flask db migrate and flask db upgrade commands
• Now lets add other two models Refer Here for the changes done
  
• Activity: Now lets create a Resource which will add the catalog brand and catalog type (POST, GET, PUT)
• In this we have implemented the Get and Post for the CatalogBrand. Refer Here for the changes
• Try to implement the Same for the Catalog Type