DiskFileSystem uses TranslateExceptions
Moved #access_denied_error rom Error to Session, whence it came.
Fix typo in comment
Rake checks that gems are installed
Cleanup rake definition for default task
Features which test the example fail more usefully when the example dies
Removed dead code from FtpServer
server can be bound to other than just the local interface
Can bind example to specific interface and/or port
Example can be run with no TLS, implicit TLS, or explicit TLS