Added ability for user to edit, delete posts

*Added dependent destroy so that posts are deleted along with text/link_posts
*Only allow owner of post to edit/delete
*add edit form, then removed form into partial for both edit and new
*Fix bug relating to redirect_to @post after commenting
adding rails 12 factor for deployment to heroku
Merge pull request #16 from DK-2K14/ks-edit-delete-posts

Added ability for user to edit, delete posts