Adding a method to pass in different ShortWeekdays into CalendarPickerView

Includes unit tests
The problem with this is that there will be a chance that the user could get locale's to be out of sync. DateFormatSymbols takes a Locale and so does the init() method.

    DateFormatSymbols symbols = new DateFormatSymbols(Locale.getDefault());
    symbols.setShortWeekdays(....);
    view.init(minDate, maxDate, Locale.getDefault())
            .setShortWeekdays(symbols);