[RFD] JSON output produced by --format should not prettify values

I noticed this a couple of times, but didn't open an issue yet; when using the --format option on commands, and requesting json output, the values included in the output should output the raw values, not the formatted output as is used in other formats.

For example:

$ docker ps --format '{{json .}}' | jq . 

{
  "Command": "\"nginx -g 'daemon of…\"",
  "CreatedAt": "2017-11-07 13:30:41 +0100 CET",
  "ID": "6f02a463250c",
  "Image": "nginx:alpine",
  "Labels": "com.docker.swarm.task=,com.docker.swarm.task.id=gwbj2pzql8r6ovcyw2s61piyy,com.docker.swarm.task.name=myservice.1.gwbj2pzql8r6ovcyw2s61piyy,maintainer=NGINX Docker Maintainers <docker-maint@nginx.com>,com.docker.swarm.node.id=url9rx710g8azgnhpmpr9hqfl,com.docker.swarm.service.id=2plef0c7wdya64ball1an4u2j,com.docker.swarm.service.name=myservice",
  "LocalVolumes": "0",
  "Mounts": "",
  "Names": "myservice.1.gwbj2pzql8r6ovcyw2s61piyy",
  "Networks": "one",
  "Ports": "80/tcp",
  "RunningFor": "3 minutes ago",
  "Size": "0B",
  "Status": "Up 4 minutes"
}

The RunningFor, Size, and Status output should print the "raw" information as obtained from the container, and ID should show the un-truncated ID.

Perhaps not the best example, as RunningFor is a calculated value, but opening this for discussion.

Start by tracing the --format entry point used by docker ps and reproduce the JSON example from the issue. Compare the formatted and raw behavior for RunningFor, Size, Status, and ID; done requires an agreed definition of raw values and verification that JSON output preserves them.