Adding interval objects now correctly updates the model and refreshes the data displayed in the sub view controller
Tapping an existing interval in the subview now properly propagates the data to the detail view. However, editing this information will create a new interval object rather than updating the original one
Switched to loading existing interval title into text field by calling ViewWillAppear instead of ViewDidAppear to get rid of performance hiccup that displayed empty text box before loading the interval title