Take entire connection URL from an env var

[Emersont1]

voting/common/common.go

Lines 23 to 30 in 32be358

	var (
	username = os.Getenv("MONGO_USER")
	password = os.Getenv("MONGO_PASS")
	)
	opts := options.Client().ApplyURI(fmt.Sprintf("mongodb+srv://%s:%s@cluster0.q5uor.mongodb.net/hacksoc?retryWrites=true&w=majority", username, password))
	log.Println("connecting to mongodb database...")

Currently, It's tied to the server, we can't use anything other that that mongodb atlas instance (i.e) we can't swap to a local version of mongodb if we want/need to