Rather than reimplementing the property functions in two different languages - and potentially having compatibility issues - standardize on golang for the implementation through the use of a generated binary.
This also implements all the list functions for use with shell-based plugins.
Note that the interface to the prop binary is experimental, and it should not be used directly.
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 can be useful in cases where a developer wishes to see what error messages are available for a failed deploy, but does not wish to spelunk around `docker ps -a` output.
Note that the logs are not made available once a further deploy is triggered, or after the containers have been garbage collected.
- add `report` and `set` subcommands to the git plugin
- move configuring the DOKKU_DEPLOY_BRANCH to the git plugin
- implement configurable GIT_REV support
- migrate DOKKU_DEPLOY_BRANCH settings
- add a golang-compatible, shell based method of setting plugin configuration variables
Deprecates the community dokku-git-rev plugin.
Closes#2621
Refs dokku-community/dokku-git-rev#9
