workbench should not know editors plugin

workbench/plugin.js

``` js
getWorkspaceSeletionItem: function () {
    return {
        'Switc&h Workspace': ['cmnd', 'webida-lib/plugins/workbench/workspaceSelectionDialog', 'show'],
        'Save Status': ['cmnd', 'webida-lib/app', 'saveStatus'],
        '&Quit': ['cmnd', 'webida-lib/plugins/editors/plugin', 'quit']
    };
},
```

This should be corrected.
