Packages.rb - added product upgrade summary functions (bnc#883047)

- 3.1.24

(Note: the methods will be used in `yast2-update`.)
ret = status[:new].reduce([]) do |res, product|
  log.info "New product will be installed: #{product}"
  res << _("New product <b>%s</b> will be installed") % h(product_label(product))
end
```