display the usage message when called without arguments

lib/coffee_script/command_line.js

@@ -10,6 +10,9 @@
   // The CommandLine handles all of the functionality of the `coffee` utility.
   exports.run = function run() {
     this.parse_options();
+    if (!(this.sources.length)) {
+      this.usage();
+    }
     this.compile_scripts();
     return this;
   };
@@ -113,6 +116,7 @@
     var oparser, opts, paths;
     opts = (this.options = {});
     oparser = (this.option_parser = new optparse.OptionParser(SWITCHES));
+    oparser.banner = BANNER;
     oparser.add = oparser['on'];
     oparser.add('interactive', function() {
       return opts.interactive = true;