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 .
```
This allows developers to change the shell from /bin/bash to any other when executing
`dokku enter` or pre/post deployment tasks. Ideally we could detect the shells available,
but that is slow and potentially error prone.
Closes#2572
