view db/migrate/020_add_role_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 AddRolePosition < ActiveRecord::Migration
  def self.up
    add_column :roles, :position, :integer, :default => 1
    Role.find(:all).each_with_index {|role, i| role.update_attribute(:position, i+1)}
  end

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