Fix problem with setting request timeout

The original code could override the http.Timeout with
the value of 0 if the RestClient Timeout property was 0.

If RestClient.Timeout <= 0, it shouldn't override the
http.Timeout.

Author: haacked

RestSharp/RestClient.cs

@@ -369,7 +369,11 @@ private void ConfigureHttp(IRestRequest request, IHttp http)
 				http.UserAgent = UserAgent;
 			}
 
-			http.Timeout = request.Timeout == 0 ? Timeout : request.Timeout;
+			var timeout = request.Timeout > 0 ? request.Timeout : Timeout;
+			if (timeout > 0)
+			{
+				http.Timeout = timeout;
+			}
 
 #if !SILVERLIGHT
 			http.FollowRedirects = FollowRedirects;