Docker support for development, API support groups/moods

[balloob]

This adds basic Docker support for development. (this is how I dev on my Mac).

If you have Docker installed locally, all you need to test and develop the lib is to run ./script/dev_docker. It will:

• build and launch an image
• mount the source directory so you can keep editing in your host and test in the container
• the container will delete itself when exiting