Added Python 3 compatibility

Exchanged iteritems() for item() and added helper function for printing
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