Add ZA specific importers previously in SayIt.

Along with accompanying tests and management commands.
Remove sluggable requirement.

sayit now gets this from pypi and so it is pulled in.
Make the logic of which files to skip simpler

... and make it clear why they're being skipped.
Merge remote-tracking branch 'origin/remove-sluggable-requirement'
Add an option to skip committees until one with a matching name

This is useful if a particular committee is failing to parse, and you
don't want to have to go through all the earlier ones before getting to
the one that fails.
Make the committee scraper cope with UTF-8 encoded in URLs

The committee scraping was failing due to the URL:

  http://www.pmg.org.za/committees/Ad%20Hoc%20Committee%20on%20President%E2%80%99s%20Submission%20in%20response%20to%20Public%20Protector%E2%80%99s%20Report

... which has U+2019 RIGHT SINGLE QUOTATION MARK encoded in UTF-8 in it;
this caused decoding exceptions when printing out the URL.

Also, use urllib.quote(foo) instead of foo.replace(' ', '%20')
Switch the default PopIt instance to za-new-import

This is the new PopIt for South Africa, which is generated from the
Pombola database.
Reduce the memory used by za_hansard_pmg_scraper
Whitespace tidy.
Remove duplicate if condition.
get rather than filter and take first element.

It just feels more the Django way.
Use local variable, as it's there.
Remove unused imports
Wrap comment lines.
Write to self.stderr rather than printing.
Use increment operator for tidiness.
Use truthiness of list.
Small local refactor and tidy.
Don't pass url as an arg as it's stored on row.
Remove unneeded local variable.