1077506 - [RFE] Support to list details information about one specific pulp repo

https://bugzilla.redhat.com/show_bug.cgi?id=1077506
Now it is possible list information about specific repo in details, summary and specifying different fields.

This commit also contains:
- pep8
- docs
aha, I understand what you meant :) But then, I do not see the point doing https://github.com/ipanova/pulp/blob/rfe-1077506/client_lib/test/unit/client/commands/repo/test_cudl.py#L343
in the setup of each class and then not to use it.