Voting Functionality

This is a PR for all of the voting related issues - upvoting and downvoting for both articles and comments. I have four separate issues for these various features, but I have fused all of the changes into a single pull request.

Users can upvote an article:
With this feature, a user will be able to choose to 'upvote' an article. This means that they will be able to click a button to add a point to that articles score. This score will be displayed along with the title and information about the article in question.

Users can upvote a comment:
Now users can upvote comments as well as articles. The implementation will essentially be the same in this case as it was in the last issue - click a button to add to that comments score. In a similar vein as the last issue, the score of a comment will be displayed as part of the information about this comment, such as poster and date posted.

Users can downvote an article:
With the implementation of this feature, users will now be able to downvote articles in addition to upvoting them. This means that by clicking a button - distinct from the upvote button - the user will be able to channel their negativity as reduce the score of a specific article.

Users can downvote a comment:
Similar to the last issue, users will finally be able to upvote and downvote both articles and comments. Once again, a button distinct from the upvote button will be used in order to reduce the score of a particular comment.