title: laravel 4.2 regex validation
body: <p>I have rules for password, the rules is:</p>
  
  <pre><code>Only alphanumeric characters, spaces, dashes, periods, and underscores are allowed.
  </code></pre>
  
  <p>in Users model i use validation like bellow</p>
  
  <pre><code>'password'=&gt;array('required', 'min:8', 'max:20', 'regex:[A-Za-z\s\-\._]')
  </code></pre>
  
  <p>when the form submitted, it throw error <code>The password format is invalid.</code>. what could be wrong with my regex?</p>
  
  <p>PS: i input 12345678 in password field.</p>