[feature] Support kind of configuration/tags for containers being able to exclude volumes

[typoworx-de]

It would be awesome to have support kind of configuration/tags for containers being able to exclude container volumes while using 'docker-backup --all'.

The idea:
There are sometimes docker volumes that are mounted using local bind or volumes that hold very large data which isn't required to be backed up. It would be great to find ideas how to handle this.

Additionally it would be great not also to exclude whole volumes, but may be a list of paths inside a volume, which are for f.e. cached stuff, whereas the rest should be backed up.

I think about:

• container tags
• some kind of config.json defining container/excludes (may be a config.docker-backup in the volume itself?)
• ?