Rotation of video should be configurable

[zach]

Now that pretty much every cell phone has a video camera, it seems like users may want to be able to rotate their video on the client side. We should make it configurable, but maybe limit it to 90 degree increments.

[jeroen]

We can do this automatically if height > width. If we presume people hold their phones up, it should be 90deg (clockwise).

Additionally, there can be a rotation option that indeed only accepts 0, 90, 180 and 270. People can use it to override the default (0 or 90) in case we have it wrong.

[jeroen]

We cannot set the rotation on mobile devices. Users should ensure the rotation of the videos is correct (e.g. by looping them through BOTR).