Added project module concept.

A project module (eg. issue tracking, news, wiki,...) is a set of permissions that can enabled/disabled at project level.
For each project, modules can be enabled on the project settings view ('Modules' tab).
This requires a specific permission: 'Select project modules' (if this permission is turned off, only Redmine administrators can choose which modules a project uses).

When applying this migration, all modules are enabled for all existing projects.

git-svn-id: http://redmine.rubyforge.org/svn/trunk@725 e93f8b46-1217-0410-a6f0-8f06a7374b81

app/views/projects/settings/_modules.rhtml

@@ -0,0 +1,14 @@
+<% form_for :project, @project,
+            :url => { :action => 'modules', :id => @project },
+            :html => {:id => 'modules-form'} do |f| %>
+            
+<div class=box>
+<% Redmine::AccessControl.available_project_modules.each do |m| %>
+<p><label><%= check_box_tag 'enabled_modules[]', m, @project.module_enabled?(m) %> <%= m.to_s.humanize %></label></p>
+<% end %>
+</div>
+
+<p><%= check_all_links 'modules-form' %></p>
+<p><%= submit_tag l(:button_save) %></p>
+
+<% end %>