ChineseZodiac: expand trigger space with DatesRole.

This allows for entering specific dates which will be parsed into
DateTime objects for use in the calculation.

Also, switch to the DDH-standard format for the output date strings.
ChineseZodiac: improve test readability a bit.

- Switch out \x{2013} for literal en-dash, since the file is UTF8
- Switch out \s for literal space for easier reading.
Merge pull request #634 from mwmiller/chinese_zodiac_to_role

ChineseZodiac: expand trigger space with DatesRole.