make ratings polymorphic
fix bug expire answered post
remove subscriptions and related code (table still in database)
add ratings to posts; test; add to views; fix sharing-links bug
update queue page and functionality to include answered posts which fit answerable criteria.  add unqueue to states
remove reposting, fix profile average_rating bug, change language to expire from unanswer, standardize post.unavailable_users, update tests
fix merge conflicts