feat(<AZCalendarViewDelegate>) : adding new delegate

Add:
``` objc
- (void)calendarView:(AZCalendarView *) calendarView didChangeDate:(NSDate *) date;
- (void)calendarView:(AZCalendarView *) calendarView didSelectDate:(NSDate *) date;
```

Depereate:
```
- (void)calendarView:(AZCalendarView *) calendarView didSelectDay:(AZCalDay *) calDay
```
fix(example): suport for iOS7
Merge pull request #8 from azu/issues/6

feat(<AZCalendarViewDelegate>) : adding new delegate