The backupPrepareCommand and backupCleanupCommand options offer a way to
run a script to prepare for backup and then cleanup it once finish.
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Allow providing the repository as a file, useful when we don't want it
being stored in the Git repository as plain text.
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>