more styling

code/app.py

@@ -253,7 +253,7 @@ def file_size_human(num):
         num /= 1024.0
 
 def file_size_MB(num):
-    return "%0.2f"%(num/(1024*1024),)
+    return "{:,.2f}".format(num/(1024*1024))
 
 
 def file_date_human(num):