Added critical section lock in isSpent
Added critical section lock in isSpent

braydonf/bitcore-node,phplaboratory/psiacore-node,snogcel/bitcore-node-dash,phplaboratory/psiacore-node,kleetus/bitcore-node,braydonf/bitcore-node,zcoinrocks/bitcore-node,zcoinrocks/bitcore-node,kleetus/bitcore-node,phplaboratory/psiacore-node,snogcel/bitcore-node-dash,phplaboratory/psiacore-node,phplaboratory/psiacore-node