Fix average rate calculation in today's summary and update dev server config

Author: hiteshkrmsft

package.json

@@ -1,6 +1,6 @@
 {
   "scripts": {
-    "start": "servor --reload",
+    "start": "servor www --reload",
     "test": "jest",
     "test:watch": "jest --watch",
     "test:coverage": "jest --coverage"

www/js/modules/day.js

@@ -284,8 +284,8 @@ export const DayManager = {
         const labelClass = type === 'purchase' ? 'stat-value-info' : 'stat-value-success';
 
         container.innerHTML = itemsArray.map(item => {
-            const avgRate = item.rates.length > 0 
-                ? (item.rates.reduce((a, b) => a + b, 0) / item.rates.length).toFixed(2)
+            const avgRate = item.quantity > 0 
+                ? (item.totalValue / item.quantity).toFixed(2)
                 : 0;
 
             return `