Implemented pull request review comments API

Octokit/Models/Request/PullRequestReviewCommentRequest.cs

@@ -0,0 +1,31 @@
+using System;
+
+namespace Octokit
+{
+    public class PullRequestReviewCommentRequest : RequestParameters
+    {
+        public PullRequestReviewCommentRequest()
+        {
+            // Default arguments
+
+            Sort = PullRequestReviewCommentSort.Created;
+            Direction = SortDirection.Ascending;
+            Since = null;
+        }
+
+        /// <summary>
+        /// Can be either created or updated. Default: created.
+        /// </summary>
+        public PullRequestReviewCommentSort Sort { get; set; }
+
+        /// <summary>
+        /// Can be either asc or desc. Default: asc.
+        /// </summary>
+        public SortDirection Direction { get; set; }
+
+        /// <summary>
+        /// Only comments updated at or after this time are returned. This is a timestamp in ISO 8601 format: YYYY-MM-DDTHH:MM:SSZ.
+        /// </summary>
+        public DateTimeOffset? Since { get; set; }
+    }
+}