Fix warnings when creating SayIt sections in tests

The slugify function in django-sluggable would print a warning
if passed a str rather than a unicode.  Make sure that we create
sections from unicode titles in tests.
Suppress warnings from SAPersonDetail.get_recent_speeches_for_section

These warnings were just noise in the test output.
There are no country-specific tests for Libya, Nigeria or Zimbabwe

... so don't bother running them from the run-tests scripts; the
only tests reported as having been run were doctests that had
already been run anyway.