Feature: Added functionality to select time along with date

I've updated example.html to demonstrate the new functionality.

```showTime : true``` enables the time picker select lists
```minuteIncrement``` sets the minute dropdown increment (must be a number that 60 is divisible by)
```minHour``` and  ```maxHour``` limits the hour dropdown to a range (will override 12hr clock if set)

Adding ```tt``` to the date format switches the time to use a 12 hour clock, showing an AM/PM select list accordingly :)