Require uuid + move functor_task to task.py

Require details have a uuid of an originating
runner, remove tasks having there own uuid since
only when a task is added to a flow does it obtain
a uuid.

Move functor_task to task.py since it is task releated
and seems better connected in task.py instead of as its
own module.

Change-Id: I8c441e184afcdd697d077f166f2e550fcafcd385