Pulling app_instance class into its own file. It was formerly a private internal class under App.
Move responsibility for creating AppInstances out of App and into AppInstance.from_app
Add App#percent_running to return the percent of instances running
Bumping to version 4.6.0.
Fix parameter ordering in new instances call
Bumping to version 4.6.1.
Auto-merge remote-tracking branch 'upstream/master'