Allow soft deletes from any state

At some point in the past, the compute manager's delete() method had
its @check_instance_state() decorator updated to allow deletes to be
performed from any combination of vm_state and task_state.  This same
change was not made to the soft_delete() method, and so soft_delete()
is only available if the task_state is clear, meaning that instances
that are put into ERROR state with task_state set to something are
effectively undeletable, if FLAGS.reclaim_instance_interval is set to
some non-zero value (which is what causes the API DELETE call to use
soft_delete() as opposed to delete()).  This patch updates the
@check_instance_state() on soft_delete() to match that on delete(),
and fixes bug 1029130 and bug 1029133.  This patch also partially
fixes bug 1029132, but more needs to be done to completely fix that
bug.

Change-Id: I78878110c696280f2bc28434433814884a526264

nova/compute/api.py

@@ -824,8 +824,7 @@ def update(self, context, instance, **kwargs):
         return dict(instance_ref.iteritems())
 
     @wrap_check_policy
-    @check_instance_state(vm_state=[vm_states.ACTIVE, vm_states.STOPPED,
-                                    vm_states.ERROR])
+    @check_instance_state(vm_state=None, task_state=None)
     def soft_delete(self, context, instance):
         """Terminate an instance."""
         LOG.debug(_('Going to try to soft delete instance'),