heroku/heroku — pull request #1003 by max (2014-01-17 22:38:49+00:00)
Title: Rename 16X dynos to PX dynos

We are going to have to cut a new release to rename the command line shorthand for performance dynos to `PX` instead of `16X`. So far I've only updated the usage output but it looks like we're casting the dyno size to an integer so more work needs to be done.