Prototype use of Selectors from Presentation API for video and audio transformations

[jronallo]

Description

See #51 which is a todo to create a mock-up of the use of Selectors for video and audio.

This issue is to have prototype implementations in the client which look at the selector and perform the transformations.

Variation(s)

• video
• audio
• video with no audio?
• just the audio from a video?

Proposed Solutions

There are some quick examples here for how these could be implemented in a prototype:
http://ronallo.com/blog/client-side-video-tricks/
They're naive implementations, but could be enough to show this working with a group of different selectors (cropping out a region + playing only a portion of a video) rather than just one type of transformation at a time.

Additional Background

Example of rotation in Image API using a selector pattern.
http://iiif.io/api/presentation/2.1/#rotation