Added search and replaced categories with maintained lists

I've added the ability to search youtube videos submitted to reddit.  

I've also added a "subreddit discovery" feature and a "gaming videos" category to replace the old method of categories.  This polls two multireddits I've created on reddit where I can combine a number of subreddits into one group.  I figured this would be easier than submitting a pull request every time a new game comes out and a new subreddit develops.  I can now just add that subreddit to the multireddit I curate.

Some unnecessary files were deleted that the old method of categories relied upon.