[merged from 1.9.3 branch] security fix: never unregister the "public" user session
refactored the sessionService to use a correct singleton initialization scheme. Added true authentication to ResourceHandler.
Merge 1.9.2 changes back into the trunk
change unregister error message to be an info message
Add user name to SessionData object
Add session validation to metacat tpc and workflow scheduler. Fix sanparks skin session management so it always uses the logged in session id.
Add session Validation action and session timeout functionality.
Create database and shared directories for database management code and shared code respectively.
Implement stop method in services. Stop all services when shutting down metacat. This primarily keeps scheduler from hanging with open threads.
Roll back replication user changes. Fix code that converts access levels to integer and to text.
Introduce replication user. Use the fileutil writer methods instead of writing directly.
Handle sessions with null ids gracefully.
Check for null session ID when touching session.
Implement refresh methods inherited from base class
Change the ServiceInterface into a base class called BaseService. All services extend BaseService.
Fix comments
Add comments. Added getPublicSession method
Merge 1.9 changes into Head