Fixed: CPDatePicker doesn't have a focusRing when editing

Previously, the CPDatePicker didn't have a focus ring when an user was editing it.
Now it does. It works for Aristo1 and Aristo2.

Test App in Tests/Manual/CPDatePickerTest

Fixed #2263
Merge branch 'FocusRingDatePicker' of https://github.com/Dogild/cappuccino into FocusRingDatePicker