* DeclarativeUserProfileProvider passes its ID to DeclarativeUserProfileModel, so this also works for derived classes.
* Moved creation of declarative user profile model to a protected factory method to allow subclasses to provide their own implementation.
* Added integration tests for custom user profile
* configured declarative-user-profile as default user profile provider in test servers
* Restore previously configured default provider after test with special provider settings
* Some refactoring in SpiProviderSwitchingUtils