Active Support Reloader

This class defines several callbacks:

to_prepare -- Run once at application startup, and also from
+to_run+.

to_run -- Run before a work run that is reloading. If
+reload_classes_only_on_change+ is true (the default), the class
unload will have already occurred.

to_complete -- Run after a work run that has reloaded. If
+reload_classes_only_on_change+ is false, the class unload will
have occurred after the work run, but before this callback.

before_class_unload -- Run immediately before the classes are
unloaded.

after_class_unload -- Run immediately after the classes are
unloaded.