Delay kit initialization until after the UI is up

This can potentially be expensive, so delay it.

Side effect is that the "History:" label in the Search Result
OutputPane is now correctly rendered:-) That was broken since
the Kit initialization triggered an event loop to be run too
early by running a SynchronousProcess.

Change-Id: I905c33c6facbbe03f22b9860c277ec658af9326e
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>