Merge pull request #383 from aaronmell/SentinelFixes

Sentinel GET-MASTER-ADDR-BY-NAME throws exception when service name i…

StackExchange.Redis/StackExchange/Redis/ResultProcessor.cs

@@ -1237,6 +1237,11 @@ protected override bool SetResultCore(PhysicalConnection connection, Message mes
                             return true;
                         }
                         break;
+                    case ResultType.SimpleString:
+                        //We don't want to blow up if the master is not found
+                        if (result.IsNull)
+                            return true;
+                        break;
                 }
                 return false;
             }