changed some assignments to use the repository interface instead of the implementation class.
separate CSV fields using a single quote and trim the result strings.
this is really a CSV file repository. we can make this file repository more generic by extracting the file parser (the Strategy Pattern).
added EmployeeRepository.getEmployeesBornOn() so that the filtering logic can be kept inside the repository implementations and the birthday service doesn't have to concern itself with that; changed Employee.isBirthday() to only accept month and day of month.
prevent dumbster from depending on any outdated dependencies, namely javax.mail:mail:1.3.2:jar.