Isolate postgres and enable mysql & sqlite through docker

docker-compose-generator/docker-fragments/postgres.yml

@@ -6,6 +6,11 @@ services:
     image:  postgres:9.6.5
     volumes:
       - "postgres_datadir:/var/lib/postgresql/data"
+  btcpayserver:
+    environment:
+      BTCPAY_POSTGRES: User ID=postgres;Host=postgres;Port=5432;Database=btcpayserver${NBITCOIN_NETWORK:-regtest}
+    links:
+      - postgres
 
 volumes:
     postgres_datadir: