Combine results with Jshint results

[svenackermann]

Please see https://github.com/gonsfx/gulp-jscs-stylish#combine-results-with-those-of-jshint for a way to combine jshint and jscs results. I would love to see a possibility to do the same with polylint results. This would also remove the need for a fail reporter (#2), because jshint's fail reporter can be used.