fix(calendar): Update ngModel instead of ctrl.date on input change

Current behavior doesn't propagate user input to ng-model when a valid
date is entered.

Author: Michael Chen

src/components/datepicker/datePicker.js

@@ -213,7 +213,7 @@
       self.inputElement.size = inputString.length + EXTRA_INPUT_SIZE;
 
       if (self.dateUtil.isValidDate(parsedDate) && self.dateLocale.isDateComplete(inputString)) {
-        self.date = parsedDate;
+        self.ngModelCtrl.$setViewValue(parsedDate);
         self.$scope.$apply();
       }
     });