Implemented feature request involving automatic deletion of transfer history...

Implemented feature request involving automatic deletion of transfer history and fixed TestJob member function

Toggling and setting of automatic deletion can be done under Settings->Configure KGet->Advanced.
Users can set automatic deletion based on a period of time.
For history items which have been around for a period longer than the specified duration, they are automatically deleted.
The specified duration can either be in terms of Day(s), Hour(s), Minute(s) or Seconds(s).

(Not related to bug) Also changed TestJob member function to prevent "Finished" jobs from being "Stopped" and started again. Thus resolving unit test failures.

BUG:197358
(cherry picked from commit a50d60ae)