Feature: Added product Stock Keeping Units to prevent duplicate products. A lot of refactoring because of this.

Removed: Reset Stock as it was never used and don't think it is even needed with this new batch system.
Fix: Incentive update was not working

overlord/src/app/purchase/purchase.component.html

@@ -134,7 +134,7 @@
         <!-- Product Column -->
         <ng-container matColumnDef="product">
           <mat-header-cell *matHeaderCellDef>Product</mat-header-cell>
-          <mat-cell *matCellDef="let row">{{ row.product.name }}</mat-cell>
+          <mat-cell *matCellDef="let row">{{ row.batch.sku.name }}</mat-cell>
         </ng-container>
 
         <!-- Quantity Column -->