[#4180] Move the CSS and JS includes to the layout hooks.

app/views/contracts/edit.html.erb

@@ -9,7 +9,3 @@
 <% semantic_form_for resource, :url => contract_path(@project, resource), :html => {:class => 'tabular'} do |form| %>
 <%= render :partial => 'form', :object => form, :locals => {:cancel_path => contract_path(@project, resource)} %>
 <% end %>
-
-<% content_for(:header_tags) do %>
-  <%= stylesheet_link_tag "redmine_contracts", :plugin => "redmine_contracts", :media => "screen" %>
-<% end %>