Benign org.acegisecurity.AccessDeniedException clutter Bamboo logs

Full 218 line stacktrace can be found at https://paste.atlassian.com/view/12677

On Bamboo startup in OnDemand, this AccessDeniedException is thrown and logged on a freshly provisioned instance.

If this exception is not exceptional, it would be beneficial to not print it at all. Keeping stacktraces reserved for exceptional circumstances makes it easier to spot if there is an actual issue on application start, without having to mentally sift through known benign stacktraces for each application. It also prevents us from logging half a million unhelpful log lines across OnDemand every five minutes.