DragonFlyBSD - Install Firefox syncserver with PostgreSQL

This article has been inspired by this article and by the official documentation of Mozilla Firefox syncserver. After reading the article by Mirabelette, I thought it would be nice to have my own syncserver, the only difference is that: I run DragonFlyBSD I want a PostgreSQL database as I know how to make backups of it. That led me to two different steps : building syncserver under DragonFlyBSD making syncserver use PostgreSQL as its database instead of SQLite.