This allows folks to later investigate why the rename failed (probably an app bug) and helpfully posts the container logs.
If multiple containers fail, they may have a ton of output, but this is better than not knowing what is going on.
Closes#3900
Added a quote around the "$EXPECTED" to deal with text with restricted characters. While deploying a Spring Boot application, the content of the built-in health check is {"status":"UP"}. Unfortunately all my checks failed, because for some reason the comparison didn't like this content.
remote: ! http://localhost/actuator/health: expected to but did not find: "{"status":"UP"}"
remote: ! Check attempt 7/10 failed.
After making this change, it works: I'm assuming the difference is that the presence of the quote characters in the content.
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 .
```
