title: IntegerField and required validator unintuitive? Always required?
body: <p>When I use a <code>wtforms.IntegerField</code> with <code>required</code> validator, I only ever get the message "this field is required".</p>
  
  <p>On the other hand, it seems like an <code>IntegerField</code> can only be required and that I'm not supposed to use a required validator.</p>
  
  <p>What's the logic here? Doesn't it make sense that this field just adds an is integer validator, and it should still be usable as a required field (but must be int) or not required field?</p>
  
  <p>Just trying to spot some patterns here.</p>
  
  <h2>Update:</h2>
  
  <ul>
  <li>WTForms version is <code>__version__ = '1.0.5'</code>  </li>
  <li>Flask_WTF version is <code>__version__ = '0.9.3'</code> </li>
  </ul>
  
  <h3>Form</h3>
  
  <pre><code>class OrderForm(Form):
      order_number = wtforms.IntegerField('Order Number', validators=[validators.Required()])
  </code></pre>
  
  <h3>View</h3>
  
  <pre><code>    def render_response(self):
          ctx = {}
          order_form = OrderForm()
          ctx['order_form'] = order_form
  
          if order_form.validate_on_submit(): pass
              # stuff.
          return render_template('support/warranty_form.html', **ctx)
  </code></pre>
  
  <h3>Template</h3>
  
  <pre><code>{% macro render_field(field) %}
      &lt;div class="form-field-wrapper"&gt;
          &lt;div class="form-field"&gt;
              {{ field(**kwargs) }}
          &lt;/div&gt;
          {{ render_field_errors(field) }}
      &lt;/div&gt;
  {% endmacro %}
  
  {{ render_field(order_form.order_number, placeholder="ORDER NUMBER") }}
  </code></pre>
  
  <p>If I remove the required validator, my form still requires the value.</p>
  
  <p><img src="https://i.stack.imgur.com/IX6AO.png" alt="enter image description here"></p>
  
  <p>I have just used a custom validator on a text field instead.</p>