Added new internal service for status codes.

* The Service base class now has a initialize method.
* The Status code service allows easy access to status
  codes and status message. This can be achieved by
  calling service.STATUS to access the code or
  service.STATUS_MESSAGE to access the status message.
Refactored code to use status codes.

* Added MakeflowLog for better handling of makeflow logs.
* Makeflow logs can now be parsed into a graph structure
  for further analysis.
* MakeflowLog class is now used to check the status of a
  current makeflow.
* Workflow scheduling now returns a status message.
* Workflow persistence has been disabled.
* A job can now be overwritten.
* When a workflow fails to be generated it now returns None
* A Makeflow log is checked before running a makeflow.
* Cleaned up code for using new StatusService.