Fixes#2957
- replace `docker stop` with `weaveuitl stop-container`
- replace `docker kill` with `weaveutil kill-container`
- replace `docker rm` with `weaveutil remove-container`
- replace `docker run` with minimal `weaveutil container-run`
- replace `docker inspect -f {{.ID}}` with `weaveutil container-id`
- replace data-only container `docker create` with `weaveutil create-volume-container`
- remove `docker inspect` dependencies from `weave` script
`rewrite_etc_hosts` and `with_container_fqdn`
- rework `weave` script `check_running` and `check_not_running` to use `weaveutil`
- rework `weave version` to use `weaver` /report API or `weaver --version` if not running
- rework `weave setup`'s `docker pull` to run locally rather than in `weaveexec` container
Note: we no longer need to detect awsvpc when launching.
The "AWS VPC" mode is now set via the `--awsvpc` flag.
Before we had to "detect" it when the proxy was potentially started
later, after the router had started.
We drop WEAVEPROXY_DOCKER_ARGS as obsolete.
They seem to stop Docker using its build cache.
Removing the line entirely stops weaveproxy from working, as it
assumes it can exec `./weave` from the current directory.
Marc Carré