PostgreSQL: add handler for error/close event

Signed-off-by: swpd <swpdtz@gmail.com>
add postgresql to build target

Signed-off-by: swpd <swpdtz@gmail.com>
PostgreSQL: update README.md to explain the usage

Signed-off-by: swpd <swpdtz@gmail.com>
PostgreSQL: change style for method names

Signed-off-by: swpd <swpdtz@gmail.com>
Merge commit '7af2931f33dbe66cd7757a2c535b8661a1ef54bd' into postgresql
PostgreSQL: remove unnecessary spaces

Signed-off-by: swpd <swpdtz@gmail.com>
Merge commit '773b7b41d395110fb785b4ca156456eaa848fbf7' into postgresql