Feature Request: read docker configuration file when about to launch a new job

[lhernanz]

The Docker configuration containing the registry credential is only used when starting Ofelia via an init block in runjob.go. That means that is Ofelia is a long running process, it will not notice any potential change in the credentials to use.

The request here is to re-read the config fail just before a new image is going to be pulled from the registry. This will ensure that the latest credentials are always used.

Thanks!