Make this definition match the rest.

All the other instances of CandidateInfo declare it as a class. This
doesn't break anything, but changing it gives clang one less warning to
scream about.
Only start mongod and rabbitmq if necessary.

On Ubuntu, installing these packages starts them immediately so there's
no point starting them in the install and init scripts here. On Mac the
situation is a little more complex because it's a manual step to make
something installed from homebrew run as a service. Account for both
cases in the scripts.
Merge pull request #86 from byronclark/clang-warnings

Make this definition match the rest.
Merge pull request #87 from byronclark/system-started-services

Only start mongod and rabbitmq if necessary.
Added cleanup option in installation scripts to remove downloaded
libraries
Added cleanup option to vagrant script
Fixed cleanup script option