Changed to display copied modules as part of the copy command

Corresponds to: https://github.com/pulp/pulp/pull/415

The approach here was nearly identical in concept to the one in pulp_rpm, so I'll just copy the notes from that PR:

There was already a hook in PollingCommand to handle the task end result. This was implemented to use a separate module for rendering the units. That rendering is kept separate because my next round of changes will be to the unassociate units flow to return the units as well, so that rendering is going to be needed for that command as well.