1..7
 -  throws a sfValidatorError if you don't pass a from_date and a to_date option
 -  throws a sfValidatorError
# ->clean()
 -  returns the from and to values
 -  throws a sfValidatorError if the from date is after the to date
 -  throws a sfValidatorError
# Custom field names options
 -  take into account custom fields
 -  returns the from and to values for custom field names
# Looks like everything went fine.