Use Puppet-Datatype Sensitive for Passwords

• add Parameter "sensitive" to Function postgresql_password to decide if its Returnvalue should be of Datatype Sensitive
• let defined Type postgresql::server::role accept Datatype Sensitive for $password_hash
• let defined Type postgresql::server::db accept Datatype Sensitive for $password
• let Class postgresql::server accept Datatype Sensitive for $postgres_password
• let defined Type postgresql::validate_db_connection accept Sensitive for $database_password