WIP - localhost exception

These changes fix the functional test suite.  I'm still working on the rest of our tests, but if you see any patterns forming in my fixes that I should avoid, please let me know!  I wanted to open the code review on this because it's a lot of changes.
put return on the line above, to parallel:
https://github.com/mongodb/mongo-ruby-driver/pull/448/files#diff-c839d9243a66575aae6640fce8b3b511R235