Maid 22 bad alloc

https://maidsafe.atlassian.net/browse/MAID-22

the verification involves using routing_node network across droplets

it may worth to check whether the routing_node network (using next branch) suffers the same issue as using interim_merge_of_unsafe_packet_loss_tolerance branch.
If not, then no need to merge this MAID-22_bad_alloc branch into next.

when socket->HandleReceiveFrom itself got executed, socket* still points to a valid instance.
However, when one thread dived into HandleReceiveFrom and carrying out sub-tasks, the socket instance may be asked to carry out a destruction, which cause problem.
Actually, segfault is also raised (from the subtasks inside HandleReceiveFrom).
This forced me to put an additional catch(...) wishing it can be caught.
(I know it is not good to use catch(...), however I was told *Socket will be removed totally later on,
so here we are only looking for a temp solution to get routing_node network up running)