Implement functionality for comments on posts

[robertlent]

Comments are rendered in the following way: {Posted User's Name} said: {comment} {Date Posted} at {Time Posted}

The Posted User's Name is dynamic, based on the logged in user, printing 'You' if the logged-in user posted it, and the user's username if not. This logic is also present on the feed page, rendering as: Posted by {you or username} {title} {image} {caption}