Clean up models, routes and controllers of join tables that aren't being used

[jordan-castelloe]

Context

We created files for join table models, controllers, and routes. We don't need them! Let's get rid of them!

Process

Controllers

1. Delete product_orderCtrl.js
2. Delete employeeComputerCtrl.js
3. Delete employeeTrianingProgramCtrl.js

Models

1. Delete EmployeeComputersModel.js
2. Delete EmployeeTrainingProgramsModel.js
3. Delete ProductOrdersModel.js

Routes

1. Delete routes/employeeComputers.js
2. Delete routes/employeeTrainingPrograms.js
3. Delete routes/productOrders.js

Expected Result

The files should be gooooone.