Add "!reddit <subreddit>" command

[cuijulian]

There should be a !reddit command which takes in the name of a popular subreddit and outputs the top few posts in that subreddit (bolded title and link to post). Functionality would be almost identical to !news and !fakenews, would be strongly recommended to make use of existing code. Refer to NewsParser.java, News.java, and FakeNews.java for implementation. Great for new contributors who want to dabble in their first feature.

[justinmcook]

For those interested in working on this: Reddit RSS feeds are available at: https://reddit.com/r/<subreddit>.rss (which also means !reddit could take in any word rather than a predefined list like !news and !fakenews)

[justinmcook]

See #16 for a similar issue