Add a script in bin directory that can be called manually to turn a
replica into a primary. Being able to turn a replica into a primary
is an absolutely necessary feature of replication. It's a necessary
step of a takoever procedure.

Questions remain for automatisation. One option is to provide a url
the user may simply interact with (clickable button ...) to trigger
the script, that may also be used automatically as part of a larger
takoever procedure.

Triggering the change to primary by editing the instance parameters
- such as by removing the replication-related parameters - does not
seem best: one immediate drawback is the uncertain propagation time
of instance parameters; another is the reliance on the availability
of the SlapOS master to trigger a usually time-sensitive operation.