dark kde/plasma theme and the context view

[Mathias Panzenböck]

Currently some text in the contextview is barely readable when you use a dark 
kde theme and a fitting plasma theme. See:
https://web.student.tuwien.ac.at/~e0427417/images/amarok-dark-theme.png

I think the bluish background of the contextview should be somehow derived from 
the kde/plasma theme so that the text always stays readable. Is it maybe 
possible to just load the global plasma theme? I'm still somewhat new to this 
(the only code I touch in amarok is the podcast support).

	-panzi