Indicate pre-selected multi-value item

Issue #32 

Last selected item has a checkmark next to it and when a new item is selected the background goes gray. Once the user goes back to the home tableview of the debug menu the checkmark will update to the new selection and will display accordingly the next time they open the multi-value item tableview
Don't animate this unless the `animated` flag is true. You can just set the duration to 0 if not animated to make it simpler.