Add the association between customer and sales_order models.
Update the index page of admin/customers.
Add sales_orders info.
Remove some unimportant columns.
Update the index page of admin/sales_orders.
Add items count and remove institution column.
Update sales_agents index page.
Merge branch 'master' of https://github.com/upsilon2gamma/abgent-website-cn
Create admin/statistics controllers.
Generate the statistics of products.
Add jqplot lib (version 1.0.8r1250).
Add numeric_utilities.js.
Plot charts for products statistics.