In Admin/Tools/More I found the Sopport tool. It is its description:
The Support tool integrates with the Ticket tool to provide customers a support ticket system for submitting and following issues, bugs, and feature requests. Customers get a personal view of the tickets that they submit.
Unfortunately, I don't see that users can vote up/down the features (or bugs) they prefer. Is it possible to do it with Assembla or we must use an external tool?