pass :strict to RDiscount

Gives up the ability to use particular formatting inside of words in
order to prevent turning everything into a list that shouldn't be,
like a single "K." comment.

Closes lobsters#217

extras/markdowner.rb

@@ -7,7 +7,8 @@ def self.to_html(text, opts = {})
       return ""
     end
 
-    args = [ :smart, :autolink, :safelink, :filter_styles, :filter_html ]
+    args = [ :smart, :autolink, :safelink, :filter_styles, :filter_html,
+      :strict ]
     if !opts[:allow_images]
       args.push :no_image
     end