Altered views to include approximate date.

Changed the people_view and person_detail template to include approximate date instead of the birth and death year. Updated the model string method to include the approximate birth and death dates and updated the person model test to match the model string method.
Altered views to include approximate date.

Changed the people_view and person_detail template to include approximate date instead of the birth and death year. Updated the model string method to include the approximate birth and death dates and updated the person model test to match the model string method.