Construct a set of artist-instrument relations corresponding to an artist with the supplied first name
and last name and the specified instrument names.
Lists a maximum amount of 25 Songs, with the following properties:
The Songs have not been played, skipped, downloaded or requested at
all during the last two years.
The Songs have been played at least 10 times.
The list is ordered to the plays/year ratio.
Loads the users' properties file, sets the property specified
in the propName parameter to the value specified in the propValue
parameter and saves the properties file.