huginn/app/views/admin/users/_form.html.erb

<%= form_for([:admin, @user], html: { class: 'form-horizontal' }) do |f| %>
  <%= render "devise/shared/error_messages", resource: resource %>
  <%= render partial: '/devise/registrations/common_registration_fields', locals: { f: f } %>

  <div class="form-group">
    <div class="col-md-offset-4 col-md-10">
      <%= f.label :admin do %>
        <%= f.check_box :admin %> Admin
      <% end %>
    </div>
  </div>

  <div class="form-group">
    <div class="col-md-offset-4 col-md-10">
      <%= f.submit class: "btn btn-primary" %>
    </div>
  </div>
<% end %>

<hr>

<div class="row">
  <div class="col-md-12">
    <%= link_to icon_tag('glyphicon-chevron-left') + ' Back'.html_safe, admin_users_path, class: "btn btn-default" %>
    <% if @user.persisted? && @user.active? && @user != current_user %>
      <%= link_to 'Become User', switch_to_user_admin_user_path(@user), class: "btn btn-default btn-info", data: { confirm: 'This will log you in as another user. Would you like to continue?' } %>
    <% end %>
  </div>
</div>