* TestGetLicenseFileFromDisk: avoid using fileutils.FindConfigFile
* config: abstract config-related file access, extend memory store
* simplify config validate to avoid file knowledge
* fix relative file tests
* cluster: fix ConfigChanged event
The old and new configurations were swapped when notifying the enterprise code of configuration changes, creating needless instability in propagating config updates across a cluster.
* config/database: ignore duplicates
* test cleanup
* remove unnecessary Save() in test