ManagementActor now drops the central definition cache post-commit (via the existing
AfterConfigurationCommit seam) after every external system, external-system method and
database connection create/update/delete, so an edit takes effect on the editing node
immediately instead of after DefinitionCacheTtl. ManagementService gains a project reference
to ExternalSystemGateway. The other central node still converges within the TTL.
Joseph Doherty