cli: cluster-delete -m /var/reana:/var/reana

[tiborsimko]

The cluster creation command (cluster-create) or the run CI command (run-ci) have an option to share a cluster directory with the host system. The typical usage is -m /var/reana:/var/reana so that /var/reana would be persistent and easily accessible from host.

The cluster deletion command (cluster-delete) does not have this option, which sometimes lead to a situation where /var/reana/... remains populated with old instance content, which may not be always wanted.

Currently we do things like:

$ reana-dev run-ci -m /var/reana:/var/reana --exclude-components=r-a-vomsproxy,r-a-krb5 -c r-d-helloworld
...
$ reana-dev cluster-delete
$ sudo rm -rf /var/reana/*

The aim of this issue is to introduce exactly the same -m option for consistency, so that one could do:

$ reana-dev cluster-delete -m /var/reana:/var/reana

Note that the parameter is of the format -m local_path:cluster_nodepath, so one has to delete only local_path/*.

Note that this may require to use sudo.