Make survey_planner.py aware of completed actions

[trey0]

Currently, survey_planner.py will always try to accomplish all goals in its problem instance, even if the completed-x predicates for some of the goals have been asserted in the problem instance. The desired behavior is to skip over these already-completed goals.

Relevant predicates it should pay attention to are completed-panorama and completed-stereo.

We should also add at least one minimal test problem instance that includes a completed goal and check that the planner successfully returns a plan without the action corresponding to that goal.

[trey0]

Closed by #132