1152633 - Pulp Yum plugin can now find consumer.conf settings correctly

https://bugzilla.redhat.com/show_bug.cgi?id=1152633

This change adjusts the Pulp Yum plugin to use the read_config method. This area of the code has no test coverage I can find today, and with this small of a change I don't think this is worth writing test code for.

I tested the behavior, and the profile works as expected with this change.

There are 3 tests that do fail, but those are already broken in the parent of this commit. The broken parent is 59edf68e74d63298e63dcc70a00ca19ffd59be88.