var gulp = require('gulp');
var source = require('vinyl-source-stream');
var browserify = require('browserify');
var streamify = require('gulp-streamify');
var uglify = require('gulp-uglify');
var sass = require('gulp-sass');
var prefix = require('gulp-autoprefixer');
var rename = require('gulp-rename');
var gutil = require('gulp-util');
var webpack = require('gulp-webpack');

gulp.task('scripts', function() {
  browserify('./static/js/app.js')
    .bundle()
    .pipe(source('js.min.js'))
    //.pipe(streamify(uglify()))
    .pipe(gulp.dest('./static/build'));
});

gulp.task('css', function() {
  gulp.src('./static/sass/style.scss')
    .pipe(sass({
      outputStyle: 'compressed',
      errLogToConsole: true,
      error: function(err) {
        console.log(err);
      }
    }))
    .pipe(prefix("last 1 version", "> 1%", "ie 8", "ie 7"))
    .pipe(rename('css.min.css'))
    .pipe(gulp.dest('./static/build'));
});

gulp.task('webpack', function(callback) {
  return gulp.src('./static/js/app.js')
    .pipe(webpack({ /* webpack configuration */ }))
    .pipe(uglify())
    .pipe(rename('js.min.js'))
    .pipe(gulp.dest('./static/build'));
});

// Watch
gulp.task('watch', function() {

  // Watch .scss files
  gulp.watch(['static/js/**/*', 'static/sass/**/*'], ['css', 'scripts']);

});

gulp.task('default', ['scripts', 'css']);

var gulp = require('gulp');
var source = require('vinyl-source-stream');
var browserify = require('browserify');
var streamify = require('gulp-streamify');
var uglify = require('gulp-uglify');
var sass = require('gulp-sass');
var prefix = require('gulp-autoprefixer');
var rename = require('gulp-rename');

gulp.task('scripts', function() {
  browserify('./static/js/app.js')
    .bundle()
    .pipe(source('js.min.js'))
    //.pipe(streamify(uglify()))
    .pipe(gulp.dest('./static/build'));
});

gulp.task('css', function() {
  gulp.src('./static/sass/style.scss')
    .pipe(sass({
      outputStyle: 'compressed',
      errLogToConsole: true,
      error: function(err) {
        console.log(err);
      }
    }))
    .pipe(prefix("last 1 version", "> 1%", "ie 8", "ie 7"))
    .pipe(rename('css.min.css'))
    .pipe(gulp.dest('./static/build'));
});

// Watch
gulp.task('watch', function() {

  // Watch .scss files
  gulp.watch(['static/js/**/*', 'static/sass/**/*'], ['css', 'scripts']);

});

gulp.task('default', ['scripts', 'css']);

--- 
+++ 
@@ -6,8 +6,6 @@
 var sass = require('gulp-sass');
 var prefix = require('gulp-autoprefixer');
 var rename = require('gulp-rename');
-var gutil = require('gulp-util');
-var webpack = require('gulp-webpack');
 
 gulp.task('scripts', function() {
   browserify('./static/js/app.js')
@@ -31,14 +29,6 @@
     .pipe(gulp.dest('./static/build'));
 });
 
-gulp.task('webpack', function(callback) {
-  return gulp.src('./static/js/app.js')
-    .pipe(webpack({ /* webpack configuration */ }))
-    .pipe(uglify())
-    .pipe(rename('js.min.js'))
-    .pipe(gulp.dest('./static/build'));
-});
-
 // Watch
 gulp.task('watch', function() {
 
Add in webpack in there.
