title: ESLint not resolving absolute file path for extends
body: <p>I'm attempting to get a local <code>eslintrc</code> (in my project root) to extend my global <code>eslintrc</code> (located at <code>~/.eslintrc</code>).</p>
  
  <p>Here's the local <code>eslintrc</code>:</p>
  
  <pre><code>{
    "extends": "~/.eslintrc"
  }
  </code></pre>
  
  <p>Here's the error I'm getting when running <code>eslint foo.js</code>:</p>
  
  <pre><code>Cannot read config file: /Users/cbickel1/dev/learning/webpack-demo/~/.eslintrc
  Error: ENOENT: no such file or directory, open '/Users/cbickel1/dev/learning/webpack-demo/~/.eslintrc'
  Referenced from: /Users/cbickel1/dev/learning/webpack-demo/.eslintrc
  Error: Cannot read config file: /Users/cbickel1/dev/learning/webpack-demo/~/.eslintrc
  Error: ENOENT: no such file or directory, open '/Users/cbickel1/dev/learning/webpack-demo/~/.eslintrc'
  Referenced from: /Users/cbickel1/dev/learning/webpack-demo/.eslintrc
      at Object.fs.openSync (fs.js:558:18)
      at Object.fs.readFileSync (fs.js:468:33)
      at readFile (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:70:24)
      at loadLegacyConfigFile (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:142:44)
      at loadConfigFile (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:222:22)
      at load (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:505:18)
      at configExtends.reduceRight (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:391:36)
      at Array.reduceRight (native)
      at applyExtends (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:362:28)
      at Object.load (/Users/cbickel1/.nvm/versions/node/v7.4.0/lib/node_modules/eslint/lib/config/config-file.js:536:22)
  </code></pre>
  
  <p>Looks like ESLint isn't correctly resolving the path given as absolute. What should I do?</p>