Fixed #19823 -- Fixed memcached code example in cache docs
Fix filtering during collection of paths in setup.py

Thanks Marek Brzóska for the report.
Fixed #19822 -- Added validation for uniqueness on USERNAME_FIELD on custom User models.

Thanks to Claude Peroz for the draft patch.
Fixed #19829 -- Fixed index lookups for NumPy arrays in templates.
Put unicode_literals into all formats.py
Merge pull request #728 from jphalip/ticket-19829

Fixed #19829 -- Fixed index lookups for NumPy arrays in templates.
Updated FormattingTests test case to use settings contexts
Fixed #17217 (again): accept usual space in localized forms with locales which has non-breaking space as THOUSAND_SEPARATOR