create category actions/validations/views
add post actions/validations/views
create necessary category routes
extract form errors to a partial
add comment actions/views/routes
extract set_post before_action
render post with empty comment, needed for comment form helper
continuity fix
Redirect, rather than render.  Disallows resubmission on refresh.
display comments creation form
visual cleanup
categories#show
allow post/category association
extract post details to partial
set @categories for selection on posts#new and posts#edit
associate selected categories to post
stylize category links
stylize comments
code styling
use require in strong parameters