Refactor the MethodValidate method

[4k1k0]

Right now the MethodValidate method has a switch case with a lot of boolean logic and is difficult to read.

I propose using validation functions for each case. So instead of

case ccDigits.At(4) == 4011 || ccDigits.At(6) == 431274 || ccDigits.At(6) == 438935 ||
		ccDigits.At(6) == 451416 || ccDigits.At(6) == 457393 || ccDigits.At(4) == 4576 ||
		ccDigits.At(6) == 457631 || ccDigits.At(6) == 457632 || ccDigits.At(6) == 504175 ||
		ccDigits.At(6) == 627780 || ccDigits.At(6) == 636297 || ccDigits.At(6) == 636368 ||
		ccDigits.At(6) == 636369 || (ccDigits.At(6) >= 506699 && ccDigits.At(6) <= 506778) ||
		(ccDigits.At(6) >= 509000 && ccDigits.At(6) <= 509999) ||
		(ccDigits.At(6) >= 650031 && ccDigits.At(6) <= 650051) ||
		(ccDigits.At(6) >= 650035 && ccDigits.At(6) <= 650033) ||
		(ccDigits.At(6) >= 650405 && ccDigits.At(6) <= 650439) ||
		(ccDigits.At(6) >= 650485 && ccDigits.At(6) <= 650538) ||
		(ccDigits.At(6) >= 650541 && ccDigits.At(6) <= 650598) ||
		(ccDigits.At(6) >= 650700 && ccDigits.At(6) <= 650718) ||
		(ccDigits.At(6) >= 650720 && ccDigits.At(6) <= 650727) ||
		(ccDigits.At(6) >= 650901 && ccDigits.At(6) <= 650920) ||
		(ccDigits.At(6) >= 651652 && ccDigits.At(6) <= 651679) ||
		(ccDigits.At(6) >= 655000 && ccDigits.At(6) <= 655019) ||
		(ccDigits.At(6) >= 655021 && ccDigits.At(6) <= 655021):
		return Company{"elo", "Elo"}, nil

It could change to

case isElo(ccDigits):
    return Company{"elo", "Elo"}, nil

[4k1k0]

Solved on #6