Encapsulate the Tello demo in a Docker image

**Is your feature request related to a problem? Please describe.**
Users currently have to download Homebrew, ffmpeg, Node.js and other tools. We should package this all in Docker. This also helps support Windows users.

**Describe the solution you'd like**
Create a Dockerfile that captures all the steps.

**Describe alternatives you've considered**
Platform-specific instructions

**Additional context**
The trained visual recognition model should also be shared through the IBM Model Asset Exchange as a Docker image.