Ideally python usage goes away - the dokku-installer should become a mandatory cli command, and the plugin is rewritten in golang - but for now, we need to use the correct binary when running dokku.
Closes#3714
This PR uses the new syntax for commands introduced in Docker 1.13, making it a bit easier to understand just what a particular command is trying to do.
This also pushes the long-form syntax for docker command flags, which are also easier to understand at a glance.
This will allow background processes to cleanup these files if they were unable to be cleaned up during a run of the dokku binary, as is the case for files copied by the docker binary when running in docker.
This change allows operators to specify a DOCKER_BIN environment variable. This will specify a binary to run when executing docker, which is useful in cases where the 'docker' command being run must be modified in a way that would otherwise be invasive to Dokku, but minimalistic if done within a wrapper.
While I do not agree with _every_ style change, this will force Dokku to have consistent formatting across all shell scripts, which is arguably a Good Thing™.
The command used to reprocess everything is:
```shell
shfmt -l -bn -ci -i 2 -w .
```
Often-times, we will want to have the container inspect output for debugging purposes, but this process is:
- error prone, as the user needs to know what their containers are
- potentially insecure, as the output must be sanitized of sensitive data
Instead of making users wade through this process, we provide a helper `ps:inspect` command, that can be used to diagnose problems associated with containers that may or may not exist for an application.
