Removed u'' string literal prefixes from the default values of
settings.CAPTCHA_OUTPUT_FORMAT since they are invalid syntax on Python
2.3 which is still the stable Python version for Debian and lots of
people use it.
Removed the rest of the u string literal prefixes.
Revert "Removed the rest of the u string literal prefixes."

This reverts commit e1ad702ec0e6b2869549191e33d0f876c75fb93f.
Replaced all of the u string literal prefixes with six.u() calls and now
all tests pass on all supported environments.
Made .sh scripts executable
Changelog