CORAL-140: implement equals and hashCode for anonymous Principal
implementation returned by SubjectImpl.getPrincipal()
CORAL-140: use correct time units when setting up session pool
CORAL-140: new default settings for session eviction: check every 15
seconds, retain sessions for 60 seconds, check 25% of existing sessions
on each eviction run, no sessions are retained indefinitely.
CORAL-140: coral sessions pool statistics for Munin