M101: exclusive access for mission execution

Initial version mainly for review. Probably easier to review if you look at the individual commits in their order.

All mission execution tests are now going through the request for exclusive access and *no* exceptions are generated. As suggested, this request is based on the ORG.acquire_resource call (and not via the negotiate call). However, there's some ad hoc mechanism to get a negotiation_id that is required by the acquire_resource call. More details in the code comments and TODOs.

@mmeisinger / @edwardhunter  please review.

@bobfrat FYI