Student tied to entity

students are now tied to entities.  this required the following changes:
-plugins be registered as internal or external
-users be admins or not
-ui updates to the dashboard, new admin command to add/remove admins
-student auth data models and auth utils
-api now intercepts any messages with 'student_id'
-student management now adds auth info for sender and internal plugins

minor changes:
-student_model_tutor had the hard coded ID changed; this is a pretty worthless tutor now that it can't access other entity's students, but its there anyway
-win_manager, changed 'plugin' to 'entity' when failed to close