Move build task to gulp

tasks/gulp-build.js

@@ -0,0 +1,18 @@
+import gulp from 'gulp';
+require('gulp-grunt')(gulp);
+
+gulp.task('build', () => {
+  if (process.env.NODE_ENV === 'production') {
+    gulp.start('build:prod');
+  } else {
+    gulp.start('build:dev');
+  }
+});
+
+gulp.task('build:dev', (done) => {
+  gulp.start('grunt-build:dev', done);
+});
+
+gulp.task('build:prod', (done) => {
+  gulp.start('grunt-build:prod', done);
+});