Vid 1996 reduce duplicate DOM selectors based on Yellow Lab data

http://yellowlab.tools/ called out a number of duplicated DOM selectors on our site. I did a brief audit of this and ended up focusing on ArtcleComments, removing one query for "#WikiaArticleComments" and for 4 queries for "#article-comments-ul". I also did some general code cleanup while I was at it. 

Note: the way this JS is initialized is a little funky, so it wasn't as straight forward to make sure we cache jQuery DOM objects.