<form method="POST" action="{{ post_url }}" class="form-horizontal">
    {{ form.hidden_tag() }}
    {% for field in form if (field.widget.input_type != 'hidden' and field.widget.input_type != 'submit') %}
        <div class="control-group{% if field.errors %} error{% endif %}">
            {{ field.label(class="control-label") }}
            <div class="controls">
                {{ field }}
                {% for error in field.errors %}
                    <span style="color: #B94A48;">{{ error }}</span>
                {% endfor %}
            </div>
        </div>
    {% endfor %}
    <div class="control-group">
        <div class="controls">
            {% for field in form if (field.widget.input_type == 'submit') %}
                {{ field(class="btn") }}
            {% endfor %}
        </div>
    </div>
</form>
<form method="POST" action="{{ post_url }}" class="form-horizontal" role="form">
    {{ form.hidden_tag() }}
    {% for field in form if (field.widget.input_type != 'hidden' and field.widget.input_type != 'submit') %}
        <div class="form-group{% if field.errors %} has-error has-feedback{% endif %}" id="{{ field.name }}_top">
            {{ field.label(class="col-sm-1 control-label") }}
            <div class="col-xs-3">
                {% if field.type == 'TextField' or field.type == 'TextAreaField'  %}
                    {{ field(class="form-control", **{'type': 'text'})|safe }}
                {% elif field.type == 'BooleanField' %}
                    {{ field(type="checkbox") }}
                {% else %}
                    {{ field(class="form-control") }}
                {% endif %}
                {% for error in field.errors %}
                    <span class="form-control-feedback">{{ error }}</span>
                {% endfor %}
            </div>
        </div>
    {% endfor %}
    <div class="form-group">
        <div class="col-sm-offset-1 col-xs-2">
            {% for field in form if (field.widget.input_type == 'submit') %}
                {{ field(class="btn btn-primary") }}
            {% endfor %}
        </div>
    </div>
</form>

Rework form to be used for BS3
Rework form to be used for BS3
