adjust UI on iPhone X

adjust UI on iPhone X, and can set cancel and ok button's color or text.

All DateTimePicker Mode

• DatePickerDateMode
• DatePickerTimeMode
• DatePickerDateTimeMode
• DatePickerYearMonthMode
• DatePickerMonthDayMode
• DatePickerHourMinuteMode
• DatePickerDateHourMinuteMode
• 开发设置topView的背景颜色和按钮颜色

Fixed some bugs

1. Fixed this bug #3.
2. Set the default time.