Added Screen Lock

Fixed bug where camera was not released correctly when the application
closed (prev. commit)
Fixed application for SCREEN_LOCK, if the screen turns off then the
camerea can not record or detect motion.
Added a simple text overlay to the RTSP Server.

Added a simple text overlay to the RTSP Server.

It seems that this slows down the stream a little bit.  I think I need
to investigate how to improve performance. I am
doing alot of image processing that might be able to be shared among the
different services, this may provide a nice
performance boost.