support touch delegate

Currently , `<AZCalendarViewDelegate>` only support did change day delegate.

Adding a new touch event delegate to `<AZCalendarViewDelegate>` .


``` objc
@protocol AZCalendarViewDelegate <NSObject>
@optional
- (void)calendarView:(AZCalendarView *) calendarView didChangeDate:(NSDate *) date;
- (void)calendarView:(AZCalendarView *) calendarView didSelectDate:(NSDate *) date;

- (void)calendarView:(AZCalendarView *) calendarView didSelectDay:(AZCalDay *) calDay __attribute__((deprecated("Use - (void)calendarView:didChangeDate: instead")));
@end
```