make it so that you can get a random quote if you don't specify a category

systems/quote.rb

@@ -19,12 +19,12 @@ module QuoteSystem
     category = message[0]
     quote = message[1..].join(" ")
     event.channel.send_message("I'm adding the quote '#{quote}' under the category #{category}")
-    db.execute("INSERT INTO quotes (author, category, quote) VALUES (?, ?, ?)", [event.author.id, category, quote])
+    db.execute("INSERT INTO quotes (author, category, quote) VALUES (?, ?, ?)", [event.author.id, category.downcase, quote])
     nil
   end
 
   command :quote do |event, *message|
-    category = message[0]
+    category = message[0].downcase
     if category == nil
       quotes = db.execute("SELECT * FROM quotes")
       quote = quotes.sample