Fixed: CPDatePicker send an action with the methods setObjectValue: and setDateValue:

Previously, the CPDatePicker sent an action to the target when the method setObjectValue: and setDateValue were called.
Now it sends the action only when the user makes an action.

Fixed #2206
Merge pull request #2210 from Dogild/CPDatePicker-action

Fixed: CPDatePicker send an action with the methods setObjectValue: and setDateValue: [+1]