It looks like Serenity is no longer being developed—the addon is completely gone from Curse now. But the good news is, about a month ago JS came back to WoW and started back with development of the original JS Hunter Bar!
JS posted this comment on the addon’s page a couple weeks ago:
I left Serenity in other people’s hands when i stopped playing.
When i got back, I did not want to interfere with their work, if they decide to continue.
Also, Serenity has had issues with the curse downloader and conflicts with an old (dead) priest addon.
JSHB was the logical choice for which I maintain.
I for one am thrilled JS is back, he’s the original developer of this all-in-one hunter addon and Flippy did a great job maintaining it for the last year while JS was gone, but it’s awesome to have the original dev working on it again. Welcome back to the game, JS! We missed you!
You can download JS Hunter Bar on curse here: http://www.curse.com/addons/wow/js-hunter-focus-bar
Old news, but it’s new to me… I only just noticed this thanks to one of my followers, Mistressmorbid. Thanks a ton for the heads up! I’ve edited my 5.0 post to include this new information.