add FractionCalculator.java
Mini program invoke test in FractionCalculator...
See FractionCalculator.java commit message for record of the
program output.
Idea and minimal skeleton. Test output...
...from FractionCalculatorTest

$ java -ea FractionCalculatorTest
FractionTestCalculator tests verbose output:
debug call to evaluate with inputString ="quit"
debug quitProgram = true