Ground work for Wino Calendar. (#475)

Wino Calendar abstractions.

Wino.Core.Domain/Models/Calendar/CalendarPageNavigationArgs.cs

@@ -0,0 +1,10 @@
+namespace Wino.Core.Domain.Models.Calendar
+{
+    public class CalendarPageNavigationArgs
+    {
+        /// <summary>
+        /// When the app launches, automatically request the default calendar navigation options.
+        /// </summary>
+        public bool RequestDefaultNavigation { get; set; }
+    }
+}