Maid 366 crash in parallel receive test

The main commit which should take care of crashes is the [Adds lock inside ManagedConnections::StartNewTransport](https://github.com/inetic/MaidSafe-RUDP/commit/c4252f1b0f99a17d5fa6d47b10088cc74c8b34fb), but when I tested it alone I saw some other crashes, so I'm bundling the other commits into this pull request as well.