Ocre Runtime: Support HTTP GET of wasm containers.

[PatrickRobbIOL]

Use case

For various reasons (development process, production usage of Ocre, CI/CD processes) it would be beneficial to be able to GET a wasm container image over HTTP from the Ocre Shell running on a device, and start a container from that image.

Describe the solution you'd like

1. From ocre shell, make HTTP request to some URI from a server which will server a wasm image over http
2. Start a container from this wasm image.

Additional context

Providing support through a conventional container registry is also possible, but these work on another protocol (not http), and Stephen mentioned that this makes implementation additional work.

[kr-t]

I agree. I am preparing a specification of list of commands both for this and #33 tasks, in order to have more runtime functionality for container management. ocre pull or ocre get would be one of the essential ones.