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

db/migrate/068_create_enabled_modules.rb

@@ -0,0 +1,18 @@
+class CreateEnabledModules < ActiveRecord::Migration
+  def self.up
+    create_table :enabled_modules do |t|
+      t.column :project_id, :integer
+      t.column :name, :string, :null => false
+    end
+    add_index :enabled_modules, [:project_id], :name => :enabled_modules_project_id
+    
+    # Enable all modules for existing projects
+    Project.find(:all).each do |project|
+      project.enabled_module_names = Redmine::AccessControl.available_project_modules
+    end
+  end
+
+  def self.down
+    drop_table :enabled_modules
+  end
+end