Fixed bugg category change. Changed pause function.

When songs are added and category changed new songs will not play.
Bugg is fixed.
When pause is pressed buttons are still dissabled and previous and
next song has functionality.

 Incheckare: Marcus <marcux@localhost.localdomain>

 På grenen master
 Ändringar att checka in:
   (använd "git reset HEAD <fil>..." för att ta bort från kö)

	ändrad:     ui/mainWindow.py