Feed Creation: Add a separate extension call for namespace stuff. Change extensions accordingly.
Entry creation: Entries create their own XML Element, which is put into the feed by the caller
Merge branch 'master' of https://github.com/snipem/python-feedgen into merge-test
Fix issues with python3

The introduced way of printing things in python3 would work for byte
arrays but not for simple strings. This patch fixes this issue.

Signed-off-by: Lars Kiesow <lkiesow@uos.de>
Fixed some typos