Moving classes into core-implementations

[Maximilian Kossick]

I do not think moving *everything* in Amarok's source tree into
core-implementations. It will end up being just another dumping
ground.

In particular, stuff like AudioCdCollection is definitely not core, as
it is going to be completely useless on e.g. mobile devices.

Can we revert that commit please and discuss where all those other
classes should end up.

Cheers,
Max