COMMODITIES-Down as Cyprus rattles markets again; gold rallies

* Oil, copper down again after Wednesday rebound * Gold jumps on safe-haven demand; soy rallies too By Barani Krishnan NEW YORK, March 20 (Reuters) - Oil and metals prices fell back on Thursday while gold rallied as financial markets were gripped by fresh worries of a potential financial meltdown in Cyprus and the impact that may have on the euro zone's fragile recovery. The dollar resumed its upward trend versus the euro, making commodities denominated in the greenback less att