add .DS_Store files
add comment model, add comment_spec
add has_many assocciation in article and user model
add comment_controller,
add comment_controller_spec,
show comments in article's show view,
add feature create_new_comment
use counter cache for comments
use user scope for atricles in articles controller
Merge pull request #4 from AmirMingaliev/add-comment-model

Add comment model