added ofxQTVideoSaver addon

[atduskgreg]

Hey Kyle,

I added ofxQTVideoSaver to the project along with the necessary image buffer and other code for actually recording a movie of the screen.

It's in the week3 version of the project.

I'm not 100% sure what your policy is on adding addons. What's a good way to include them in the repo? I added ofxQTVideoSaver to my xcodeproject, but it's just pointing at the copy in my addons directory. If there's some better way of shipping the addons with the project, let me know.

Thanks,

Greg