TLS connection to Postgresql

In order to configure TLS connection to Postgresql take next steps:

[Optional] pass environment variable DATABASE_CERTS_PATH, default is /opt/explorer/db-certs
put certificates into folder specified by DATABASE_CERTS_PATH. There should be three files:
- client-cert.pem
- client-key.pem
- server-ca.pem
pass environment variable DATABASE_SSL_ENABLED=true