Not support composite targets

[Andrew Abramov]

nodeConfig.addTech([require('enb-stylus/techs/css-stylus'), {
    target: '?.css' // urls should be handled relative to this file
}]);

nodeConfig.addTech([require('enb-stylus/techs/css-stylus'), {
    target: '.tmp/no-prefix.css' // urls should be handled relative to this node, 
                                 // but not `node/.tmp` directory
}]);