maven setup
test for 1 => I
impl: returning hardcoded "I"
triangulation: more tests for single symbol conversion
sloppy impl: using if
refactoring: using hashmap
tests for all single symbols
test: repeating: 2 => II etc
impl: using LinkedHashMap
refactoring: using value objects for symbols
test: combining symbols: 15 => XV etc
impl: using StringBuilder
refactoring: encapsulating some logic in RomanSymbol
refactoring: removing not necessary if
refactoring: nicer symbol repetition logic
test: subtractive notation: 4 => IV etc
surprising impl :-)
additional test: 4999 => MMMMCMXCIX