view db/migrate/023_add_tracker_is_in_roadmap.rb @ 1087:74407a04925c issue_540

* (publication.rb) - fixed the acts_as_activity query (see diff to previous commit) - not returning duplicate results any longer; added the visible scope to the publication model;
* (init.rb) - created a new public permission - view_publication.

class AddTrackerIsInRoadmap < ActiveRecord::Migration
  def self.up
    add_column :trackers, :is_in_roadmap, :boolean, :default => true, :null => false
  end

  def self.down
    remove_column :trackers, :is_in_roadmap
  end
end