Check that client is playing the right item

Send date when playback command is emitted
Rename some classes

MediaBrowser.Model/Syncplay/PlaybackRequest.cs

@@ -0,0 +1,34 @@
+using System;
+
+namespace MediaBrowser.Model.Syncplay
+{
+    /// <summary>
+    /// Class PlaybackRequest.
+    /// </summary>
+    public class PlaybackRequest
+    {
+        /// <summary>
+        /// Gets or sets the request type.
+        /// </summary>
+        /// <value>The request type.</value>
+        public PlaybackRequestType Type;
+
+        /// <summary>
+        /// Gets or sets when the request has been made by the client.
+        /// </summary>
+        /// <value>The date of the request.</value>
+        public DateTime? When { get; set; }
+
+        /// <summary>
+        /// Gets or sets the position ticks.
+        /// </summary>
+        /// <value>The position ticks.</value>
+        public long? PositionTicks { get; set; }
+
+        /// <summary>
+        /// Gets or sets the ping time.
+        /// </summary>
+        /// <value>The ping time.</value>
+        public long? Ping { get; set; }
+    }
+}