Replace doesExist() definition and usage in blueprints/ember-cli-jsdoc/index.js

[notmessenger]

Replace with https://github.com/ember-cli/exists-sync

[notmessenger]

Can this be of any use?

    isDirectory: function( aPath ) {
        try {
            return fs.statSync( aPath ).isDirectory();
        } catch ( e ) {
            if ( 'ENOENT' === e.code ) {
                return false;
            } else {
                throw e;
            }
        }
    }