added models and controllers for comments and todo-items
added comment controller tests
added tests for todo_items controller
created controller actions in todo_items and comments, added views, all test passing
added test to todo_items controller to test creating a new todo_item
added todo_item controller create action, forms and javascript to create a new todo_item in the todo_items controller and display it
added a test and fixed the view to test to make sure the newly created todo_item is desplayed after creating it