Document how to setup pop on its own without buffalo

[KrzysztofMadejski]

As follows I guess:

	// Option 1: connecting to db specified in database.yml
	pop.LoadConfigFile()
	db, err := pop.Connect("development")

	// Option 2: connecting to db specifying all params  
	cd := pop.ConnectionDetails{
		Dialect:  "postgres",
		Host: "localhost"
	}
	db, err = pop.NewConnection(&cd)
        db.Open()