Create Subjectable concern and include it in Resource, LessonPlan, and Profile models to DRY them up
Clean up LessonPlan, Resource, and Profile models by adding Newsable concern
Removes news_items_observer, Adds Newsable concern. Fixes subjects bug that allowed subjects to appear in view dropdown lists more than once.
Removes multi_search_item_observer and adds Searchable concern
Adds observers for LessonPlan, Resource, and Profile models and moves callbacks into them