Changes related to task cancellation

Changes:
* Scheduler will NOT allow update of running but non-cancelable tasks
* EndState and eventing reflecting what tasks "knows" (ie. is unaware of cancelation)
* Future.cancel(true) will not behave as documented: with true will interrupt the thread (but doing that is dangerous)
Two YUM task made cancelable

By making the work into unique tmp directory (using repo tmp directory)
and as last step, moving the data in proper place.
Fixes to file moves
Fix deletion, should be optional
Optionally move, as not always repodata is created
Removed unused import, no code change
Merge remote-tracking branch 'origin/master' into cancellation-fixes
Logging cleanup

The proper logging as at INFO now for State, runState is at DEBUG
Use the TaskInfo from context.

As the listener instance might be replaced, by reschedule or
task update.
Refine state

Ironically, comment was already correct but not the code
Remove for now the checkState

Will see is it needed in there, and than to solve
events differently.
More logging
Logging and removal fixes

As by mistake I left the removal on setNexusTaskState, that was in case
of canceled and replaced task deleting the _new_ task.
Fix test

As it had wrong assumption about future and task state when
canceled WITH interruption.
Simplify thread hand-off and remove thread when done

To not allow it lingering around, as a stale future
might cancel it when it's already executing another
task.
Applied Stuart's comments and more.
Enhance transition logging

If task ended, include endState, if avail
Debug (to be removed)
Logging improvements
Handle properly premature cancelation

At the moment QZ "scheduler thread" did not yet pick up
the task to be run, and is scheduled to be run at this moment
(either by "now" or it triggers now), there is a window
when the task might be canceled (prematurely). This should
not throw UnableToInterruptJobException as cancelation in
this case can be handed in NexusTaskJobSupport just fine,
even if the NX task is not cancelable.