Cleanup the setContactAvatar code
Cleanup the setContactAvatar code

Avoid using Nepomuk2::Resource, and use the DMS inbuilt expansion of
nie:urls.

leonhandreke/ktp-common-internals,leonhandreke/ktp-common-internals,KDE/ktp-common-internals,leonhandreke/ktp-common-internals,KDE/ktp-common-internals,KDE/ktp-common-internals