quickly implemented the webm format for output

[jameslporter]

I have found this useful for viewing the video files on phone and computer in the browser. Feel free to check out my web app for motion over at https://github.com/jameslporter/motionweb

[jameslporter]

I have found a bug, although not critical it makes for funny videos. The varying framerate seems to go into the new video frame for frame, even as motion adjusts(and the cam itself) the frame rate, the webm file produced isn't aware of it.