Boolean types (and possibly a few others) are returned as wrapper
classes when coming out from proto mapping; these need to be unwrapped
otherwise the caller who is expecting a nice clean boolean value ends up
with an icky protobuf class.
This fixes the shell provisioner, which relies on a communicator
receiving a settings hash `{error_check: false}` for a command that
usually fails but it sent just in case before provisioning starts.
