title: Setting error message in html with knockout validation
body: <p>I would like to use knockout-validation by only adding validation rules in HTML5, which works great:</p>
  
  <p><a href="http://jsfiddle.net/gt228dgm/1/" rel="nofollow">http://jsfiddle.net/gt228dgm/1/</a></p>
  
  <p>I would then like to change the default error messages generated by the browser (like "This field is required." or "Invalid"). This is pretty easily done in javascript code, But I believe this kind of texts should go into the HTML. Is that possible and how? I guess I'm looking for something like:</p>
  
  <pre><code>&lt;input data-bind='value: firstName, validate: { message: "Please enter first name" }' required pattern="^[A-Za-z]{1,255}$"/&gt;&lt;/label&gt;
  </code></pre>