title: eslint does not allow 4 spaces for indent
body: <p>I have installed eslint and eslint-plugin-vue for my project.
  When I load the project in the browser, I get the following warning in the console: </p>
  
  <blockquote>
    <p><a href="http://eslint.org/docs/rules/indent" rel="noreferrer">http://eslint.org/docs/rules/indent</a>        Expected indentation of 2 spaces but found 4<br>
      src\_nav.js:2:1</p>
  </blockquote>
  
  <p>This is my _nav.js:</p>
  
  <pre><code>export default {
      items: [{  /*this is line 2 - indented with 4 spaces*/
  </code></pre>
  
  <p>I have tried to tell lint that I want to use 4 spaces, but I still get the warning. I have the same problem with .vue files.</p>
  
  <p>This is my .eslintrc.js:</p>
  
  <pre><code>module.exports = {
      root: true,
      parserOptions: {
          parser: 'babel-eslint'
      },
      env: {
          browser: true,
      },
      extends: [
          // https://github.com/vuejs/eslint-plugin-vue#priority-a-essential-error-prevention
          // consider switching to `plugin:vue/strongly-recommended` or `plugin:vue/recommended` for stricter rules.
          'plugin:vue/essential',
          // https://github.com/standard/standard/blob/master/docs/RULES-en.md
          'standard'
      ],
      // required to lint *.vue files
      plugins: [
          'vue'
      ],
      // add your custom rules here
      rules: {
          // allow async-await
          'generator-star-spacing': 'off',
          // allow debugger during development
          'no-debugger': process.env.NODE_ENV === 'production' ? 'error' : 'off',
          "indent": ["error", 4],
          "vue/html-indent": ["error", 4],
          "vue/script-indent": ["error", 4],
      }
  }
  </code></pre>