Implement explicit offer operation reconciliation between the master, agent and RPs.

Upon receiving an UpdateSlave message the master should compare its list of pending operations for the agent/LRPs to the list of pending operations contained in the message. It should then build a ReconcileOfferOperations message with all the operations missing in the UpdateSlave message and send it to the agent.

The agent will receive these messages and should handle them by itself if the operations affect the default resources, or forward them to the RP manager otherwise.

The agent/RP handler should check if the operations are pending. If an operation is not pending, then an ApplyOfferOperation message got dropped, and the agent/LRP should send an OFFER_OPERATION_DROPPED status update to the master.