freeze exception for kscreensaver installation recommendation

Binary package hint: kubuntu-notification-helper

In order to resolve bug #273667 kubuntu-notification-helper requires a couple of lines changes (all not exactly potential for regression though), as well as adding a patch to kdebase-workspace so that upon loading the screensaver kcm triggers the notification that recommends installing kscreensaver.

What is more troubling though. If the user decides to consider the recommendation a dialog will pop up, showing what packages ought to be installed, instead of useless package names we provide localizable strings for this dialog though.
This means that we need to add a new string for this to work properly.

It is probably worth adding this new string despite string freeze, considering this features improves user experience quite a bit. My theory is as follows: those users that care for screensavers and checkout the configuration module will be glad for an easy way to get some default screensavers (not caring much about a possible untranslated string), and those that do not care for screensavers alltogether might not open the module, much less do anything with the install-kscreensaver-notification than dismiss it.

Please also have a look at the attached diff for kubuntu-notification-helper