Changes to allow retry when protogeni nodes fail to allocate. There
are two ways this can happen. 1. When allocating the proxy nodes before getting the tickets. This is just like the local node case; need to go around the loop again and retry with a new node set. 2. When getting the tickets, someone else got the nodes and gthe getticket fails. This is a lot like case 1, but now we have to nfree the proxy node, and tell the mapper to try again.