Add DecimalObject value object library

README.md

 
 * [Brick\Math](https://github.com/brick/math) - A library providing large number support: `BigInteger`, `BigDecimal` and `BigRational`.
 * [ByteUnits](https://github.com/gabrielelana/byte-units) - A library to parse, format and convert byte units in binary and metric systems.
+* [DecimalObject](https://github.com/spryker/decimal-object) - A value object to handle decimal/float more easily and precise.
 * [LibPhoneNumber for PHP](https://github.com/giggsey/libphonenumber-for-php) - A PHP implementation of Google's phone number handling library.
 * [PHP Conversion](https://github.com/Crisu83/php-conversion) - Another library for converting between units of measure.
 * [PHP Units of Measure](https://github.com/triplepoint/php-units-of-measure) - A library for converting between units of measure.