Add missing use strict directives

Author: Turbo87

src/index.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Macros = require('./lib/utils/macros');
 const normalizeOptions = require('./lib/utils/normalize-options').normalizeOptions;
 

src/lib/utils/builder.js

@@ -1,3 +1,5 @@
+'use strict';
+
 module.exports = class Builder {
   constructor(t, options) {
     this.t = t;

src/lib/utils/macros.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const Builder = require('./builder');
 
 const DEBUG = 'DEBUG';

src/lib/utils/normalize-options.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const satisfies = require('semver').satisfies;
 
 function normalizeOptions(options) {

src/tests/debug-tools-test.js

@@ -1,3 +1,5 @@
+'use strict';
+
 const DebugToolsPlugin = require('../index');
 const transform = require('babel-core').transform;
 const expect = require('chai').expect;