Added algorithm to find gcd of two numbers

Algorithms.lua

@@ -342,3 +342,14 @@ function isFound(ary, key)
 	end
 	return false;
 end
+
+function gcd(num1, num2)
+	while((num1 ~= 0) and (num2 ~= 0)) do
+		if(num1 > num2) then
+			num1 = num1 % num2;
+		else
+			num2 = num2 % num1;
+		end
+	end
+	return num1 | num2;
+end