1.0.0

• Implemented units conversion through root unit (@SilverFire)
• Added more supported units: minute, hour, day, week, month, year, bps, kbps, mbps, gbps, kb, mb, gb, item (@hiqsol)
• AbstractQuantity implements JsonSerializable interface now (@hiqsol)
• Added Quantity::isPositive(), isNegative() methods (@hiqsol)
• Other minor enhancements and fixes (@SilverFire, @hiqsol)
• Enhanced tests coverage (@hiqsol)

0.1.0

• Added Quantity implementation and tests (@hiqsol)
• Added Unit implementation and tests (@hiqsol)