Add Post like action & link

I am not a restful maniac at all, I would have done it through a GET like hacker news do, but it's so easy with rails 4 helpers!
Add emotions to Comment model
Add controller & link to like comments
Add points_count presenter for comments
Add emotions counter cache on comments
Complete travis-ci database setup
Make test pass... still lot of clean up to do
Add fancy badges
Make test pass... still lot of clean up to do