title: webpack context and resolve.modules not resolving node_modules
body: <p>I'm trying to introduce webpack into a legacy project with the following folder structure:</p>
  
  <pre><code>-web
      -project
         - webpack.config.js
         - package.json
      -src
         - client.js
  </code></pre>
  
  <p>Everytime I run webpack --config webpack.config.js in the project folder I get the following error: ERROR in Entry module not found: Error: Can't resolve 'babel-loader\ in ......\web.</p>
  
  <p>I set the context to the web folder because it is the parent of the config and the src. I also added both the src and node modules to the resolve.modules property. Is there a configuration that I'm missing? </p>
  
  <p>My webpack config:</p>
  
  <pre><code>const path = require('path');
  
  const isProduction = process.env.NODE_ENV === 'production';
  const webpack = require('webpack');
  
  
  const babelConfig = {
    "presets": [
      "@babel/preset-env",
      "react"
    ],
    "plugins": [
      "transform-runtime",
      "add-module-exports",
      "transform-export-extensions"
    ],
    "env": {
      "development": {
        "plugins": []
      }
    }
  };
  const base = path.resolve(__dirname, '..');
  const project = path.resolve(base, 'project');
  const src = path.resolve(base, 'src');
  
  module.exports = {
    context: base,
    resolve: {
      modules: [path.resolve(project, 'node_modules'), src],
      extensions: ['.js', '.jsx']
    },
    entry: {
      plp: path.resolve(src, 'client.js')
    },
    devtool: '#inline-source-map',
    output: {
      filename     : '[name].js',
      chunkFilename: '[name].js',
      path: __dirname + "/../dist"
    },
    stats: {
      colors: true,
      modules: true,
      reasons: true,
      errorDetails: true
    },
    module: {
      rules: [{
        test: /\.jsx?$/,
        include: [src],
        use: [{
          loader: 'babel-loader',
          query: babelConfig
        }]
      }]
    },
    plugins: [
      new webpack.DefinePlugin({
        __DEVELOPMENT__: !isProduction,
        __DEVTOOLS__: !isProduction
      }),
  
      new webpack.IgnorePlugin(/webpack-stats\.json$/)
    ]
  };
  </code></pre>
  
  <p>The package.json:</p>
  
  <pre><code>{
    "dependencies": {
      "babel-cli": "^6.22.2",
      "babel-plugin-transform-es2015-modules-commonjs": "^6.22.0",
      "babel-preset-es2016": "https://registry.npmjs.org/babel-preset-es2016/-/babel-preset-es2016-6.22.0.tgz",
      "babel-preset-react": "^6.24.1",
      "react": "^16.2.0",
      "react-dom": "^16.2.0"
    },
    "devDependencies": {
      "babel-core": "^6.26.0",
      "babel-loader": "^7.1.2",
      "babel-plugin-transform-runtime": "^6.23.0",
      "babel-preset-env": "^1.6.1",
      "babel-preset-es2015": "^6.24.1",
      "babel-preset-es2017": "^6.24.1",
      "babel-preset-stage-0": "^6.24.1",
      "webpack": "^3.8.1"
    }
  }
  </code></pre>
  
  <p>Thanks in advance!</p>