Add a way to get to the comments

Octokit/Clients/IIssuesClient.cs

@@ -20,6 +20,11 @@ namespace Octokit
         /// </summary>
         IMilestonesClient Milestone { get; }
 
+        /// <summary>
+        /// Client for managing comments.
+        /// </summary>
+        IIssueCommentsClient Comment { get; }
+
         /// <summary>
         /// Gets a single Issue by number.
         /// </summary>

Octokit/Clients/IssuesClient.cs

@@ -10,11 +10,13 @@ namespace Octokit
             Assignee = new AssigneesClient(apiConnection);
             Events = new IssuesEventsClient(apiConnection);
             Milestone = new MilestonesClient(apiConnection);
+            Comment = new IssueCommentsClient(apiConnection);
         }
 
         public IAssigneesClient Assignee { get; private set; }
         public IIssuesEventsClient Events { get; private set; }
         public IMilestonesClient Milestone { get; private set; }
+        public IIssueCommentsClient Comment { get; private set; }
 
         /// <summary>
         /// Gets a single Issue by number./// </summary>