view db/migrate/021_add_tracker_position.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 AddTrackerPosition < ActiveRecord::Migration
  def self.up
    add_column :trackers, :position, :integer, :default => 1
    Tracker.find(:all).each_with_index {|tracker, i| tracker.update_attribute(:position, i+1)}
  end

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