Perform redirection completion when final link requires it

[sarroutbi]

It seems some 302 responses are returned when parsing some html files and getting links to RPMs. koji-retriever should perform the redirection automatically, similarly to how curl does with -L option:

       -L, --location
              (HTTP) If the server reports that the requested page has moved to a different location (indicated with a Location: header and a 3XX response code), this option makes curl redo the  request  on
              the new place. If used together with -i, --include or -I, --head, headers from all requested pages are shown.