core: RemoveImageParameters - added removeDuringExecution flag

Added a flag indicating whether an image should be removed during the
execute phase of the RemoveImage command or during the endSuccesfully
method.

Change-Id: I0ba734a97db220f913bdee88dbfeeba76981f5a3
Signed-off-by: Liron Aravot <laravot@redhat.com>