Adjust yo generator --help usage output

Used to still say `yeoman init` by default.

lib/base.js

@@ -461,17 +461,12 @@ Base.prototype.help = function help() {
  */
 
 Base.prototype.usage = function usage() {
-  var args = this._arguments.map(function (arg) {
-    return arg.config.banner;
-  }).join(' ');
-
-  var options = this._options.length ? '[options]' : '',
-    name = (this.namespace === 'yeoman:app' || !this.namespace) ? '' : this.namespace + ' ',
-    cmd = 'init';
+  var options = this._options.length ? '[options]' : '';
+  var name = this.generatorName ? ' ' + this.generatorName : '';
 
   name = name.replace(/^yeoman:/, '');
 
-  var out = 'yeoman ' + cmd + ' ' + name + args + ' ' + options;
+  var out = 'yo' + name + ' ' + options;
 
   if (this.description) {
     out += '\n\n' + this.description;

test/base.js

@@ -257,7 +257,7 @@ describe('yeoman.generators.Base', function () {
       var help = this.dummy.help();
 
       assert.ok(help.match('Usage:'));
-      assert.ok(help.match('yeoman init FOO one two three \\[options\\]'));
+      assert.ok(help.match('yo \\[options\\]'));
       assert.ok(help.match('A new desc for this generator'));
       assert.ok(help.match('Options:'));
       assert.ok(help.match('--help   # Print generator\'s options and usage'));
@@ -268,7 +268,7 @@ describe('yeoman.generators.Base', function () {
   describe('generator.usage()', function () {
     it('should return the expected help / usage output', function () {
       var usage = this.dummy.usage();
-      assert.equal(usage, 'yeoman init FOO one two three [options]\n\nA new desc for this generator');
+      assert.equal(usage, 'yo [options]\n\nA new desc for this generator');
     });
   });