Simple form label class - ruby-on-rails-3

Question

I want to use simple-form and bootstrap to generate a horizontal form with 2 rows. The first row should have two inputs side by side - one for first name with one label and the second row should have an input for email. My problem is that that label for the first row is not getting the control-label class that is required for the horizontal form to render correctly. However, all the proper classes are being applied to the email field.
Below is my code:
= simple_form_for #order, :url => '/product/process_order', :html => {:class => 'form-horizontal'} do |f|
.form-inputs
.control-group
= f.label :first, "Full and last name"
.controls
= f.input_field :first, :class => "span2", :placeholder => 'First'
= f.input_field :last, :class => "span3" , :placeholder => 'Last'
= f.input :email, :placeholder => 'you#example.com'
Which generates:
<form accept-charset="UTF-8" action="/product/process_order" class="simple_form form-horizontal" id="new_order" method="post" novalidate="novalidate">
<div class="form-inputs">
<div class="control-group">
<label for="order_first">Full and last name</label>
<div class="controls">
<input class="string required span2" id="order_first" name="order[first]" placeholder="First" size="50" type="text">
<input class="string required span3" id="order_last" name="order[last]" placeholder="Last" size="50" type="text">
</div>
</div>
<div class="control-group email required">
<label class="email required control-label" for="order_email">
<abbr title="required">*</abbr> Email
</label>
<div class="controls"><input class="string email required" id="order_email" name="order[email]" placeholder="you#example.com" size="50" type="email"></div>
</div>
</div>
</form>

Answer 1

In your config/initializers/simple_form.rb file, find the label class line and set it to:
config.label_class = 'control-label'
Also, if you are using bootstrap, you can do a few other things in this file. This might also help you:
SimpleForm.setup do |config|
config.wrappers :my_wrapper, :class => 'control-group',
:hint_class => :field_with_hint, :error_class => :field_with_errors do |b|
b.use :html5
b.use :placeholder
b.optional :maxlength
b.optional :pattern
b.optional :min_max
b.optional :readonly
## Inputs
b.use :label
b.wrapper :my_wrapper, :tag => 'div', :class => 'controls' do |ba|
ba.use :input
ba.use :error, :wrap_with => { :tag => 'span', :class => 'label label-important' }
ba.use :hint, :wrap_with => { :tag => 'p', :class => 'help-block' }
end
end
config.default_wrapper = :my_wrapper
config.boolean_style = :nested
config.button_class = 'btn'
config.error_notification_tag = :div
config.error_notification_class = 'alert alert-error'
config.label_class = 'control-label'
config.form_class = 'form-horizontal'
config.generate_additional_classes_for = [:wrapper, :label, :input]
config.browser_validations = true
end

Answer 2

According to this you have to do something along the lines of this:
f.label :first, label: 'Full and last name'