feat(datepicker): add the ability to disable specific days of the week t...

...o the datepicker

Change the date picker to add the ability to choose to disable specific days of the week.
Adds an option, daysOfWeekDisabled, that is a string with the default value of '' (empty string).
To disable days of the week, append the appropriate value for the day of the week that is
desired to be disabled, with 0=Sun, 1=Mon, etc. For example, to disable Sat and Sun, add the
attribute days-of-week-disabled="06" to the element when using the datepicker directive.