UserGroupMapping field instead of string to define role access + Checkstyle
Create DocumentWorkflow et PartWorkflow Services & Checkstyle:
   - Isolate WorkflowManager, DocumentWorkflowManager & PartWorkflowManager
   - Use UserGroupMapping field instead of string to define role access
   - Use DAO to load Workflow
   - Move some method of DocumentManager to UserManager
   - Some Checkstyle