Use QNetworkAccessManager for storing the files we receive instead of
directly KIO, then provide the KIO-based QNetworkAccessManager from the
daemon. This way we'll still get the KIO network-transparency, but the
library only depenends on QtNetwork, which will be easier to get in some
platforms.

After this change, we only depend on KConfig, KI18n and KCoreAddons, which
are tier1 and really easy to work with on any platform.

REVIEW: 123325