Previously serverConfigV17 used a global lock that made any instance of
serverConfigV17 depended on single global serverConfigMu.
This patch fixes by having individual lock per instances.
* Add configuration parameter "format" for db targets and perform
configuration migration.
* Add PostgreSQL `access` format: This causes Minio to append all events
to the configured table. Prefix, suffix and event filters continue
to be supported for this mode too.
* Update documentation for PostgreSQL notification target.
* Add MySQL `access` format: It is very similar to the same format for
PostgreSQL.
* Update MySQL notification documentation.
This patch fixes below
* Previously fatalIf() never writes log other than first logging target.
* quiet flag is not honored to show progress messages other than startup messages.
* Removes console package usage for progress messages.
As a new configuration parameter is added, configuration version is
bumped up from 14 to 15.
The MySQL target's behaviour is identical to the PostgreSQL: rows are
deleted from the MySQL table on delete-object events, and are
created/updated on create/over-write events.
