Add commit hash to the bottom of the about page

fixes #102

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 {