Began writting comments.php

initDB() - checks if the directory is writable, and initializes the database if
it is (this will create the database if it does not exist)

initTable() - creates a table whos rows represent comments, if it doesn't exist
already

Also added stub functions for addComment() and displayComments()
Created comments.js which currently displays the form

comments.js currently uses an event listener to wait for the page to load, then
finds the div with the id "simple_comments" and populates the comment submitting
form there.