Tax is added directly to product for sale

Auth guard and auth service simplified and fixed so that user is updated upon login
Home component changed to use square buttons
Fixed showing the totals in the bill

ng linted the project

bookie/src/app/sales/products/products.component.css

@@ -23,3 +23,8 @@
   background-color: #d32f2f;
   color: #ffffff;
 }
+
+.grey800 {
+  background-color: #424242;
+  color: #ffffff;
+}

bookie/src/app/sales/products/products.component.html

@@ -1,6 +1,7 @@
 <mat-card>
   <mat-card-content fxLayout="row wrap" fxLayoutGap="grid 20px">
-    <mat-card fxLayout="column" class="square-button" matRipple *ngFor="let item of list" (click)="addProduct(item)" [class.yellow300]="item.hasHappyHour">
+    <mat-card fxLayout="column" class="square-button" matRipple *ngFor="let item of list" (click)="addProduct(item)"
+              [class.yellow300]="item.hasHappyHour" [class.grey800]="item.isNotAvailable">
       <h3 class="item-name">{{item.name}}</h3>
     </mat-card>
     <mat-card fxLayout="column" class="square-button red700" matRipple [routerLink]="['../../menu-categories']"