title: Eslint rule to strict falsy check
body: <p>Is there a rule for <a href="http://eslint.org/" rel="nofollow">eslint</a> which makes it illegal to write:</p>
  
  <pre><code>if (somevar) { ... }
  </code></pre>
  
  <p>and enforces you to do proper falsy/truthy checks like</p>
  
  <pre><code>if (somevar === true) { ... }
  if (somevar === false) { ... }
  if (somevar === undefined) { ... }
  </code></pre>