Add function to get posts of connections by category id.
Add habtm association in/between post and keyword models; add get_keyword_ids function to post model.
Add get_posts_and_ids method to post model to make hash of connection's posts ids and keywords.
Add functions to Post model to get posts of connections with at least three matching keywords.
Refactored matches to use reject and not reject! in Post model; add function to get ids of secondary connections to User model.
Refactor primary and secondary connections functions in User model.
Refactor matches function in Post model.
Add method to get ids of tertiary connections to User model.
Abstract posts of connections methods in User model to work with any of the ids of connection methods.