\SMW\RefreshJob

Contains the same functionality

* Put the code in some sane order
* Add hasParameter/getParameter to manage access to the parameters array
* Add rudimentary test but needs some improvement to verify what's
expected of getProgress()

NOT FIXING the issue in SMWAdmin (this class is a real mess) of
accessing the job table.

Change-Id: I2405e4e908098fc40a2fa8c86ef2f24c2c0788c2