provide `api.db` (close #3)

refactor launching into lib/mongodb, combine all in onr place,
document clean shutdown strategy

Signed-off-by: Oleg Verych <olecom@gmail.com>
etc/scripts: update them to work again without 'nodenwer'

Signed-off-by: Oleg Verych <olecom@gmail.com>
etc/scripts: rename

Signed-off-by: Oleg Verych <olecom@gmail.com>