This commit adds a page view for invoices on the customer portal. Layout
is based on the invoice report to closely match what is already done in
Odoo. It replaces the old controller that returned only the pdf.
Customers should now be able to receive both.
Future commits will improve invoice page view notably in account_payment
while adding payment options in account customer portal.
Thibault Delavallée
6c7e128b33