change: make IAuthenticationService throw an IllegalArgumentException rather than an EnvironmentFailureException if retrieving information about a user fails

SVN: 5511

SVN: 5430

- DummyAuthenticationService.authenticateApplication should return a non-null value.
- Better logging in DefaultSessionManager
javadoc:
- improved in IAuthenticationService

SVN: 666

- IAuthenticationService refactored: it extends ISelfTestable and functionality previously implemented only by 'authenticate' has been splitted.

SVN: 660

change:
- Get additional information from Crowd authentication service.
- IAuthenticationService.authenticate(String, String) returns now a Principal object instead of a boolean value.
- User authentication is so no longer needed in CrowdAuthenticationService.

SVN: 478

SVN: 257

SVN: 251

SVN: 94

SVN: 44

SVN: 15