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/models/enabled_module.rb

@@ -0,0 +1,23 @@
+# redMine - project management software
+# Copyright (C) 2006-2007  Jean-Philippe Lang
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+class EnabledModule < ActiveRecord::Base
+  belongs_to :project
+  
+  validates_presence_of :name
+  validates_uniqueness_of :name, :scope => :project_id
+end