Remove SECTIONS_BY_DOMAIN_USING_TLD

[alvaroreig]

Hi there @mmagnus

I've been testing v2.7.3 and I think that, given that urlparse works perfectly, tld is not needed and therefore should be removed. It doesn't make any sense to have a third party lib when native python job does the trick, even as an option.

Therefore, I propose removing the SECTIONS_BY_DOMAIN_USING_TLD flag and always use urlparse.

Regards