Grouped Number Conversion tests, changed BigItneger to trunc to mastc…

[kpartlow]

…h integer types

Take a look at the change to floatingPointToBigInteger before merging
static BigInteger floatingPointToBigInteger(Object from, Converter converter, ConverterOptions options) {
double d = toDouble(from);
String s = String.format("%.0f", (d > 0.0) ? Math.floor(d) : Math.ceil(d));
return new BigInteger(s);
}