Add commit hash to the bottom of the about page

fixes #102

frontend/src/app/components/about/about.component.html

@@ -112,6 +112,15 @@
 
   <div [ngbNavOutlet]="nav" class="mt-2"></div>
 
-  <br> <br>
+  <br>
+
+  <div class="text-small text-center">
+    Git commit: 
+    <ng-container *ngIf="(mempoolStats$ | async) as mempoolStats">
+      {{ mempoolStats.gitCommit }}
+    </ng-container>
+  </div>
+
+  <br>
 
 </div>

frontend/src/app/components/about/about.component.ts

@@ -1,17 +1,20 @@
-import { Component, OnInit } from '@angular/core';
+import { Component, OnInit, ChangeDetectionStrategy } from '@angular/core';
 import { WebsocketService } from '../../services/websocket.service';
 import { SeoService } from 'src/app/services/seo.service';
 import { StateService } from 'src/app/services/state.service';
+import { Observable } from 'rxjs';
+import { MemPoolState } from 'src/app/interfaces/websocket.interface';
 
 @Component({
   selector: 'app-about',
   templateUrl: './about.component.html',
-  styleUrls: ['./about.component.scss']
+  styleUrls: ['./about.component.scss'],
+  changeDetection: ChangeDetectionStrategy.OnPush,
 })
 export class AboutComponent implements OnInit {
   active = 1;
   hostname = document.location.hostname;
-
+  mempoolStats$: Observable<MemPoolState>;
 
   constructor(
     private websocketService: WebsocketService,
@@ -20,6 +23,7 @@ export class AboutComponent implements OnInit {
   ) { }
 
   ngOnInit() {
+    this.mempoolStats$ = this.stateService.mempoolStats$;
     this.seoService.setTitle('Contributors');
     this.websocketService.want(['blocks']);
     if (this.stateService.network === 'bisq') {

frontend/src/app/interfaces/websocket.interface.ts

@@ -31,6 +31,7 @@ export interface MempoolBlock {
 export interface MemPoolState {
   memPoolInfo: MempoolInfo;
   vBytesPerSecond: number;
+  gitCommit: string;
 }
 
 export interface MempoolInfo {

frontend/src/app/services/websocket.service.ts

@@ -137,6 +137,7 @@ export class WebsocketService {
           this.stateService.mempoolStats$.next({
             memPoolInfo: response.mempoolInfo,
             vBytesPerSecond: response.vBytesPerSecond,
+            gitCommit: response['git-commit']
           });
         }