fix(orderbook): reject all dust peer orders

This fixes an oversight where we would only reject peer orders where
the price times quantity was below the dust limit, but not necessarily
where the quantity itself was below the dust limit.

lib/orderbook/OrderBook.ts

@@ -766,7 +766,8 @@ class OrderBook extends EventEmitter {
     }
 
     // TODO: penalize peers for sending ordes too small to swap?
-    if (order.quantity * order.price < TradingPair.QUANTITY_DUST_LIMIT) {
+    if (order.quantity * order.price < TradingPair.QUANTITY_DUST_LIMIT ||
+        order.quantity < TradingPair.QUANTITY_DUST_LIMIT) {
       this.logger.warn('incoming peer order is too small to swap');
       return false;
     }