Bugfix: Change mempool block time precision. (#650)

* Fix time precision.

* Fix rounding numbers only for minutes range.
Fix reflected avg time to ETA transactions.

* Fix now variable update.

frontend/src/app/components/mempool-blocks/mempool-blocks.component.ts

@@ -77,7 +77,6 @@ export class MempoolBlocksComponent implements OnInit, OnDestroy {
         this.mempoolBlocks = this.reduceMempoolBlocksToFitScreen(JSON.parse(stringifiedBlocks));
         this.updateMempoolBlockStyles();
         this.calculateTransactionPosition();
-        this.now = new Date().getTime();
         return this.mempoolBlocks;
       })
     );
@@ -90,6 +89,7 @@ export class MempoolBlocksComponent implements OnInit, OnDestroy {
           this.stateService.lastDifficultyAdjustment$
         ])),
         map(([block, DATime]) => {
+          this.now = new Date().getTime();
           const now = new Date().getTime() / 1000;
           const diff = now - DATime;
           const blocksInEpoch = block.height % 2016;