Gulp file with sass compilation and bootup of live-server

gulpfile.js

var gulp = require('gulp');
var sass = require('gulp-sass');
var exec = require('child_process').exec;

gulp.task('sass', function() {
    gulp.src('scss/*.scss')
        .pipe(sass())
        .pipe(gulp.dest('.'));
});

gulp.task('watch', ['sass'], function() {
    gulp.watch('scss/*.scss', ['sass']);
})

gulp.task('default', ['watch'], function() {
    exec("live-server");
});

tasks.json

{
    "version": "0.1.0",
    "command": "gulp",
    "isShellCommand": true,
    "echoCommand": true,
    "tasks": [{
        "taskName": "sass-1",
        "suppressTaskName": true,
        "args": [
            "default"
        ],
        "isBuildCommand": true,
        "showOutput": "always",
        "isBackground": true
    }]
}