Convert the given number into a roman numeral.
All roman numerals answers should be provided in upper-case.
convertToRoman(2) should return "II".
convertToRoman(3) should return "III".
convertToRoman(4) should return "IV".
convertToRoman(5) should return "V".
convertToRoman(9) should return "IX".
convertToRoman(12) should return "XII".
convertToRoman(16) should return "XVI".
convertToRoman(29) should return "XXIX".
convertToRoman(44) should return "XLIV".
convertToRoman(45) should return "XLV"
convertToRoman(68) should return "LXVIII"
convertToRoman(83) should return "LXXXIII"
convertToRoman(97) should return "XCVII"
convertToRoman(99) should return "XCIX"
convertToRoman(400) should return "CD"
convertToRoman(500) should return "D"
convertToRoman(501) should return "DI"
convertToRoman(649) should return "DCXLIX"
convertToRoman(798) should return "DCCXCVIII"
convertToRoman(891) should return "DCCCXCI"
convertToRoman(1000) should return "M"
convertToRoman(1004) should return "MIV"
convertToRoman(1006) should return "MVI"
convertToRoman(1023) should return "MXXIII"
convertToRoman(2014) should return "MMXIV"
convertToRoman(3999) should return "MMMCMXCIX"