Add volumes to machine configuration

Since in Che6 we move to multicontainer/sidecar way it become more important to be able to describe “interesting for workspace” persistence storage as a part of workspace configuration.

Currently, there are two ways to describe in a case of attaching (mounting, syncing etc) volumes (folders) with persisted data:

• /projects folder attached to “ws-agent” machine is a sign to attach identified persistence storage to it
• everything else (like an arbitrary PVC) described in an infrastructure specific recipe (docker volume mount, PVC etc).

It is proposed to add “volumes” section into workspace->environment->machine config, like:

 volumes:
    <name>:
        path:</path/to/machine's/folder>
        properties:{} - do we need that as option?

@garagatyi @sleshchenko @skabashnyuk

[garagatyi]

Would be useful to persist .m2 and other development data

[garagatyi]

@benoitf can you elaborate on how do you see it work for both openshift and docker infrastructures for some recipe supported by both, e.g. compose (not supported now, though)