Release v2.9.0

#156 Add cancelableDay
#157 Add self to actions
#159 Combine update and reset methods using arguments
#160 Add utilities and methods
#162 Refactoring/utilities and update

Added a new option cancelableDay - allows you to disable canceling the selected date by clicking again.

Big changes in how actions work. Read more in the reference api.

The reset() method has been merged with update(), and arguments to control the reset have been added to update().

Added date formatting utilities:

• parseDates - takes a date range as an argument. Returns an array of these dates;
• getDateString - takes a date as an argument. Returns a string in the format yyyy-mm-dd;
• getDate - takes as an argument a string in the format yyyy-mm-dd. Returns the full date.