Gulp not defined :  i am new to Gulp and have been struggling all day to make this work
**This is my Gulpfile.js**
<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

    'use strict';

    // Time how long tasks take. Can help when optimizing build times
    require('time-grunt')(grunt);

    // Automatically load required Grunt tasks
    require('jit-grunt')(grunt);

    module.exports = function(grunt) {
        // Define the configuration for all the tasks
        grunt.initConfig({
            pkg: grunt.file.readJSON('package.json'),

            // Make sure code styles are up to par and there are no obvious mistakes
            jshint: {
                options: {
                    jshintrc: '.jshintrc',
                    reporter: require('jshint-stylish')
                },

                all: {
                    src: [
                        'Gruntfile.js',
                        'app/scripts/{,*/}*.js'
                    ]
                }
            }
        });

        grunt.registerTask('build', [
            'jshint'
        ]);

        grunt.registerTask('default', ['build']);
    };

<!-- end snippet -->

**This my package.json**

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

    {
      "name": "conFusion",
      "private": true,
      "devDependencies": {
        "grunt": "^1.0.1",
        "grunt-contrib-jshint": "^1.0.0",
        "jit-grunt": "^0.10.0",
        "jshint-stylish": "^2.2.1",
        "time-grunt": "^1.4.0"
      },
      "engines": {
        "node": ">=0.10.0"
      }
    }


<!-- end snippet -->

**And this is the error message i get**

<!-- begin snippet: js hide: false console: true babel: false -->

<!-- language: lang-js -->

    grunt build
    Loading "Gruntfile.js"
    tasks...ERROR >>
        ReferenceError: grunt is not defined
    Warning: Task "build"
    not found.Use--force to
    continue.

    Aborted due to warnings.

<!-- end snippet -->

Pls guys i need help. am working on windows 10, so am using the command line there