Fix issue with date input

The user could select a year in which he or she was diagnosed with cancer, but the data wasn't persisting. After troubleshooting, the user migration data type for diagnosis_date was switched to integer from date, and the users#show template was altered to accommodate that change.

After most of the changes were made, a misspelling in user_params was discovered. That could be the ultimate cause for the data not persisting. However, these new changes allow the date to persist so the data type for diagnosis_date will not switched back and there will be no more troubleshooting.