Added events subpackge.

Added
=====

* New subpackage, events, defines an EventManager that manages the
  execution of event objects that implement an initialize, run, finalize
  interface.
* Added a PrinterEvent that wraps a PortPrinter class with an IRF
  interface.
* Added unit tests for EventManager and PrintEvents.
Added services module for testing.

Added
=====

* The services module provides some generic components/ports to use
  for testing.
Added PortEvent and unit tests.

Added
=====

* PortEvent class is an wrapper for a generic IRF port.
* New unit tests to make sure it works within an EventManager.
Added framework subpackage.

Added
=====

* New sub-package, framework. Right now it just contains a set_services
  function.