title: Flask-wtf upload file error
body: <p>Following <a href="https://github.com/lepture/flask-wtf/blob/v0.9.4/docs/form.rst" rel="nofollow">https://github.com/lepture/flask-wtf/blob/v0.9.4/docs/form.rst</a>
  First, I get an error message that "Error in the Project contract field - None". If I remove "validators=[FileRequired(), FileAllowed(['pdf'], 'Pdf only!')])" part, I got another error message 'unicode' object has no attribute 'filename'</p>
  
  <pre><code>    proj_contract = FileField('Project contract'), validators=[FileRequired(), FileAllowed(['pdf'], 'Pdf only!')])
  
      &lt;form method="POST" action="{{url_for('.new_project')}}" enctype="multipart/form-data"&gt; 
          {{form.proj_contract.label}}:&lt;input type="file" value="Upload"&gt;&lt;br&gt;&lt;br&gt;
          &lt;input type="submit" value="Next" name="Next"&gt;
      &lt;/form&gt; 
  
      def new_project():
          projectInfoForm = ProjectInfoForm(request.form)
          if request.method == 'GET':
              return render_template('application/project/projectinfo.html', form = projectInfoForm)
          else:
              if projectInfoForm.validate_on_submit():
                  c_filename = secure_filename(projectInfoForm.proj_contract.data.filename)
  projectInfoForm.proj_contract.file.save(os.path.join(app.config['UPLOAD_FOLDER'], c_filename))
  </code></pre>