title: How to HTML encode/escape a string? Is there a built-in?
body: <p>I have an untrusted string that I want to show as text in an HTML page. I need to escape the chars '<code>&lt;</code>' and '<code>&amp;</code>' as HTML entities.  The less fuss the better.</p>
  
  <p>I'm using UTF8 and don't need other entities for accented letters.</p>
  
  <p>Is there a built-in function in Ruby or Rails, or should I roll my own?</p>