Added error for bad argument, fixed diagnostic for '--help' message.

src/compiler/commandLineParser.ts

@@ -243,8 +243,9 @@ namespace ts {
                 "node": ModuleResolutionKind.NodeJs,
                 "classic": ModuleResolutionKind.Classic
             },
-            description: Diagnostics.Specifies_module_resolution_strategy_Colon_node_Node_or_classic_TypeScript_pre_1_6
-        }        
+            description: Diagnostics.Specifies_module_resolution_strategy_Colon_node_Node_js_or_classic_TypeScript_pre_1_6,
+            error: Diagnostics.Argument_for_moduleResolution_option_must_be_node_or_classic,
+        }
     ];
 
     /* @internal */