add test2ReturnII and refactor test
refactor change to convert to roman and decrease number
add test3returnIII
refactor create rule and IRule to convert RomanNumber
add test4returnIV and IVRule
refactor use abstract class to reduce duplicate code
refactor test by grouping case that match with rule
add testVRule and solved
add testIXRule and solved
refactor test to use assertRomanArabic
add testXRule and change loop in NumberConvertor
add anotherRule