title: Argument error in Rails w/ Sorcery
body: <p>I'm using Sorcery (0.8.2) and Rails (3.2.13). I'm creating a form with a username label and textfield. I am using sorcery for authentication purposes. </p>
  
  <p>I get the following error when trying to go to my 'login' page at <code>http://localhost:3000/login</code>: </p>
  
  <pre><code>wrong number of arguments (1 for 2..3) 
  </code></pre>
  
  <p>The browser says theres a problem at <em>line 6</em>: </p>
  
  <pre><code>3: &lt;%= form_tag author_sessions_path, method: :post do %&gt;
  4:  &lt;div class="field"&gt;
  5:      &lt;%= label_tag :username %&gt;
  6:      &lt;%= text_field :username %&gt;
  7:      &lt;br /&gt;
  8:  &lt;/div&gt;
  9:  &lt;div class="field"&gt;
  </code></pre>
  
  <p>When I click the 'login' link, I immediately get this error. Does anyone have any experience with the wrong num of arguments and a text field? </p>