add missing copyrights notes

Signed-off-by: Piotr Galiszewski <pgaliszewski@corp.bluecherry.net>
fix crash on when closing player window before video was fully
initialized

I cannot reproduce any crash in play event window with this patch
applied. Without this patch I could easily crash application with
QThread: Destroyed while thread is still running message
Merge branch 'issue-189' of https://github.com/pgalisz/bluecherry-client

Signed-off-by: Piotr Galiszewski <pgaliszewski@corp.bluecherry.net>