[Forms] Show initial value in datetime control

Initialize value for datetime control based on available
data, and keep up-to-date with changes from UI. Supports
clocks/timers, which use datetime as an entry field,
WTD-1221.

platform/forms/src/controllers/DateTimeController.js

@@ -68,13 +68,35 @@ define(
                 }
             }
 
+            function updateDateTime(value) {
+                var m;
+                if (value !== undefined) {
+                    m = moment.utc(value);
+                    $scope.datetime = {
+                        date: m.format(DATE_FORMAT),
+                        hour: m.format("H"),
+                        min: m.format("m"),
+                        sec: m.format("s")
+                    };
+                } else {
+                    $scope.datetime = {};
+                }
+            }
+
+            // ...and update form values when actual field in model changes
+            $scope.$watch("ngModel[field]", updateDateTime);
+
             // Update value whenever any field changes.
             $scope.$watch("datetime.date", update);
             $scope.$watch("datetime.hour", update);
             $scope.$watch("datetime.min", update);
             $scope.$watch("datetime.sec", update);
 
-            $scope.datetime = {};
+            // Initialize forms values
+            updateDateTime(
+                ($scope.ngModel && $scope.field) ?
+                        $scope.ngModel[$scope.field] : undefined
+            );
         }
 
         return DateTimeController;