Replace the external state_machine with an internal implementation

https://bugzilla.redhat.com/show_bug.cgi?id=1089061

This work refactored Job and its subclasses to use an internal implementation of state machine, removed the dependency of the state_machine gem.
These are signal methods. I originally placed them in StateMachine concern. Later I moved them here because most signal methods are now alias of existing methods. Initializing method is not in the common StateMachine because it is not a mediatory signal.