title: Form_for with :multipart => true spits out
body: <p>I am trying to add an Avatar Upload field to my Profile Page, but as soon as I add the <code>:html =&gt; {:multipart =&gt; true}</code> to it, it spits out an syntax error.</p>
  
  <pre><code>&lt;%= form_for(@user), :html =&gt; { :multipart =&gt; true } do |f| %&gt;
  &lt;%= render 'shared/error_messages', object: f.object %&gt;
  
  &lt;%= f.label :name %&gt;
  &lt;%= f.text_field :name %&gt;
  
  &lt;%= f.label :email %&gt;
  &lt;%= f.email_field :email %&gt;
  
  &lt;%= f.label :password %&gt;
  &lt;%= f.password_field :password %&gt;
  
  &lt;%= f.label :password_confirmation, "Confirmation" %&gt;
  &lt;%= f.password_field :password_confirmation %&gt;
  
  
  &lt;%= f.label :avatar %&gt;
      &lt;%= f.file_field :avatar %&gt;
  
      &lt;%= f.submit "Save changes", class: "btn btn-large btn-primary" %&gt;
  &lt;% end %&gt;
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>syntax error, unexpected tASSOC, expecting keyword_end
  ...end=  form_for(@user), :html =&gt; { :multipart =&gt; true } do |f...
  ...                               ^
  </code></pre>