modified, added functionality for adding questions automatically
added css for automatic questions selection
removed session invalid method
added automatic test creation functionality
added helper method for displaying error message
removed session valid method
added association of parent categories with questions
added counter_cache to associations categories, difficulty levels
used before_add and after_add callbacks of HABTM association
added button for adding questions automatically to test
added routes for adding questions automatically to test
schema modified
schema modified
added