Updated numeric filters to use label.

The numeric filter type was not using the value of the
'label' option or the attribute's translation from i18n.
It always used the method name.

lib/active_admin/view_helpers/filter_form_helper.rb

@@ -82,7 +82,7 @@ def filter_numeric_input(method, options = {})
                                   :onchange => "document.getElementById('#{method}_numeric').name = 'q[' + this.value + ']';"
       filter_input = text_field current_filter, :size => 10, :id => "#{method}_numeric"
 
-      [ label(method),
+      [ label(method, options[:label]),
         filter_select,
         " ",
         filter_input