Switch to eslint and fix a lot of linting errors.

Author: Eric Koleda

.eslintrc.js

@@ -0,0 +1,13 @@
+module.exports = {
+  "extends": "google",
+  "globals": {
+    "HtmlService": false,
+    "Logger": false,
+    "OAuth2": false,
+    "UrlFetchApp": false,
+  },
+  "rules": {
+    "comma-dangle": "off",
+    "no-var": "off"
+  }
+};

dist/OAuth2.gs

@@ -5,6 +5,7 @@ var del = require('del');
 var rename = require("gulp-rename");
 var jshint = require('gulp-jshint');
 var stylish = require('jshint-stylish');
+const eslint = require('gulp-eslint');
 
 gulp.task('dist', ['clean'], function() {
   gulp.src('src/*.gs')
@@ -19,8 +20,9 @@ gulp.task('clean', function() {
   ]);
 });
 
-gulp.task('lint', function() {
-  return gulp.src(['src/*.gs', 'test/**/*.js'])
-    .pipe(jshint())
-    .pipe(jshint.reporter(stylish));
+gulp.task('lint', () => {
+  return gulp.src(['src/*.gs', 'samples/*.gs', 'test/**/*.js', '!node_modules/**'])
+    .pipe(eslint())
+    .pipe(eslint.format())
+    .pipe(eslint.failAfterError());
 });