Adding an Item
  submittedListItem will contain an event listener.
    said listener will, upon user submission of a new item, run said item through generateItemElement.
    all new submission will be entered with the appropriate unchecked CSS tag
    generateShoppingItemsString will then run to update and compile the strings
    [STORE] will be updated.

Checking/Unchecking items
  event listener for '.shopping-item-toggle' / '.js-item-toggle' button.
    upon click Css class will be changed to the opposite of class prior to click.
    [STORE] will be updated

Deleting an item
  event listener for '.shopping-item-delete' button.
    upon click entire <li> will be deleted.
    [STORE] will be updated