Fixed keywords definition for bunny-treads post

Looks like the keywords expect space delimited.

Author: Sai Wong

_posts/2015-11-12-bunny-threads.markdown

@@ -4,7 +4,7 @@ title:        Rabbits, Bunnies and Threads
 author:       Sai Wong
 summary:      When writing Ruby, we sometimes take advantage of the single threaded nature of the environment and forget some of the pitfalls of being thread safe. When using servers such as Puma that allow us to take advantage of thread to maximize on performance, we found an issue with our Bunny implementation. The issue was identified as a documented inability for Bunny channels to be shared across threads and we developed a solution to address the issue.
 image:        http://res.cloudinary.com/wework/image/upload/s--GnhXQxhq--/c_scale,q_jpegmini:1,w_1000/v1445269362/engineering/shutterstock_262325693.jpg
-categories:   ruby, rails, bunny, rabbitmq, threads, concurrency, puma, errors
+categories:   ruby rails bunny rabbitmq threads concurrency puma errors
 ---
 
 ## Rabbits, Bunnies and Threads