Refactored name resolver for new lab names.

Added marking queue, and made tutor clients callbacks.

Code cleanup. Been playing with a few different static code analysis ...

tools.  Used them to recommend the changes made in this commit.

Split out the computer name resolving stuff. Should be easier to add ...

new resolvers if/when ITS start using their random computer names in all
labs.

Added a stress test for the BroadcastResponder.