Default import warnings

[acdha]

With a complete vanilla install, loading native tags will cause two lines on stderr:

Warning: Failed to load module "native_tags.contrib.generic_markup": No module named _markup
Warning: Failed to load module "native_tags.contrib.feeds": No module named feedparser

Not the end of the world but I think this should be silent unless the user requested those contrib modules.

[justquick]

out of the box it is a functional replacement to django-template-utils which use those libraries. you can always change the settings if it displeases you (at least its using stderr now)