Comments does not work

Committing this branch now so I can create a clean branch off of master
that does not contain any of my changes that were made in the Comments
branch. My understanding is that I need to push this branch to GitHub
for this to work.  Otherwise, if I just checkout master without
committing and pushing the comments branch, master will contain this
changes.
Completed the comments checkpoint

Got the comments working.  Had difficulties understanding the logic for
posts_controller/show action and the comments_controller/create action.
Also line 4 of the comments/_form.html.erb file is not crystal clear.
Added the validations to the comment model, but did not created a
dedicated way for those errors to display so the user knows what they
did wrong.