Initial Commit - CreateHeroDialog

Custom dialog used for hero creation. Uses a custom message layout with a editable text field for the user to enter the hero's name and a spinner to select the hero's class. The dialog will not allow the user to leave the name blank and displays an error message if they do. It's also worth noting that the order of the hero classes in the spinner (as defined in strings.xml) needs to remain the same or the values in the HeroHelper need to be updated accordingly.