Add canny edges filter
Ignore .DS_Store
Make GetCannyEdges receive a canvas instead of image/video
Create Image/VideoToCanvas components
merge @GabiThume #3
Merge branch 'gabi'
changes to VideoToCanvas #3

* new In/OutPorts format
* shutdown method is good to have for well-behaved components with
timeouts, rAF, etc.
* optional canvas input to draw to canvas already in DOM
* only create one canvas, send it to output on every draw
* only draw and send if video time has changed
* TODO spec!
longer timeout for test to pass
v 0.0.18