[Xfce-i18n] Use "Application Finder" instead of "xfce4-appfinder" in tour pages

[scootergrisen]

When I translate the strings for the tour pages like 
https://www.xfce.org/about/tour420 i notice a lot times the name of an 
application is written as the filename like xfce4-appfinder instead of 
Application Finder.

I think we should rather use the name "Application Finder" on the tour 
pages as that is what users sees when they use the desktop/mouse to 
launch applications rather than the filename of the application.