Release-As: 2.3.0

The groups table name is a reserved keyword in mysql and requires that
the table name be escaped with backticks in order to use the groups
name. Other databases such as postgres do not support the use of the
backticks in the query statements. This change renames the groups table
to ldapgroups in oder to avoid this problem altogether.

This does have a dependency on the backend sql plugins to alter the
schema to match the new name.

Signed-off-by: Billy Olsen <billy.olsen@gmail.com>
Co-authored-by: Chris F Ravenscroft <chris@voilaweb.com>

* fix: start servers on separate goroutines

* fix: listen to signals for graceful shutdowns

* fix: exit with 0 in case of programmed termination