added requirements for each class in corresponding spec file
Employee parse_data class passes tests on returning array, creating array of 5 objects from citizens.csv, and array is of Employee objects
Employee initialize method now works.  Note:  all number variables are converted to integers upon initialization.  May need to make sure this doesn't create rounding errors later when calculating taxes.  May need to convert to floats there.
added .rspec config file'
Employee initialize method handles nil values for names, and all tests pass
changed test of employees.first.class to use the be_a matcher
added quick note re whether need to test output to screen
added default values for all attributes

Needed to do this to run tests in liability_spec
liability class tests pass

Liability class has and exposes an Employee object as @employee,
amount_due, and amount_owed
tax_calculator passing most tests

TaxCalculator has class method liability, calculates amount owed, ditto
refund due, & returns a Liability instance.

Still working on making sure the liability method receives an Employee
object as an argument.
altered Liability initialize method to calculate amount due vs owed