Adding Liquid Testnet as frontend option

fixes #976

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

@@ -19,7 +19,7 @@
               <ng-template #transactionsPlural let-i i18n="shared.transaction-count.plural">{{ i }} transactions</ng-template>
             </div>
             <div class="time-difference" *ngIf="projectedBlock.blockVSize <= stateService.blockVSize; else mergedBlock">
-              <ng-template [ngIf]="network === 'liquid'" [ngIfElse]="timeDiffMainnet">
+              <ng-template [ngIf]="network === 'liquid' || network === 'liquidtestnet'" [ngIfElse]="timeDiffMainnet">
                 <app-time-until [time]="(1 * i) + now + 61000" [fastRender]="false" [fixedRender]="true"></app-time-until>
               </ng-template>
               <ng-template #timeDiffMainnet>