#4 Other users' music

[Cliff L. Biffle]

If another user's Kiwi configuration is readable, we should look at
it. If it specifies a directory of music to which we have access,
we should make it available.

This should probably not be on by default. Kiwi should also
respect a 'Do not advertise' setting in other users' kiwircs in case
the user wants to keep their homedir readable but, for whatever
reason, doesn't want their music showing up for other users.