gistfile1.js

gulp.task('watch', ['browser-sync', 'serve'], function () {
    var browserSync = require('browser-sync');

    // watch for changes
    gulp.watch([
        "app/*.html",
        "app/styles/**/*.css",
        "app/scripts/**/*.js",
        "app/images/**/*"
    ]).on('change', function () {
        browserSync.reload({stream:true});
    });

    gulp.watch('app/styles/**/*.scss', ['styles']);
    gulp.watch('app/scripts/**/*.js', ['scripts']);
    gulp.watch('app/images/**/*', ['images']);
    gulp.watch('bower.json', ['wiredep']);
});

1. Upgrade to BrowserSync 0.8.2
2. move var browserSync = require('browser-sync'); at the top of your gulpfile
3. replace browserSync.reload({stream:true}); with just browserSync.reload();
4. don't watch css files with gulp, put .pipe(browserSync.reload({stream:true})) in your sass task.

Thanks!