add ajax to post_voting & comment_voting
Merge branch 'master' of https://github.com/jamescheuk514/postit

Conflicts:
	app/views/comments/_comment.html.erb
	app/views/comments/undo_vote.js.erb
	app/views/comments/vote.js.erb
	app/views/posts/_post.html.erb
	app/views/posts/undo_vote.js.erb
	app/views/posts/vote.js.erb