Allow cluster definition to specify > 1 instances of a container

[makeusabrew]

Some clusters may well want several instances of a container running, particularly those which are replicas or workers etc. This should be specified on a per-cluster basis, and if used would cause containers to be suffixed ".1", ".2", ".3" etc.

[alexandrosm]

Awesome. Had coded that into my half-baked pre-decking solution but didn't end up needing it yet so didn't bring it up, but it is something that would be nice to have in the future.

[makeusabrew]

This is in release 0.0.9, although has a few rough edges. At the moment it's in at cluster level (since that makes sense; a "prod" cluster might want a higher N of nodes than dev) but causes problems if a container binds fixed ports to the host, since they'll conflict with each other.

Closing for now but the next step would be to allow some sort of configuration templating where the "index" of a multi node can be inserted (e.g. for port offsets, logfile offets, whatever).