Enable passing an options object to `config.ssl`

You'll notice that according to the rethinkdbdash README.md (line 170-171)

ssl may also be an object that will be passed as the options argument to tls.connect

https://github.com/neumino/rethinkdbdash/blame/master/README.md#L170-171

This modification enables passing an object via a JSON string, while continuing to support simple truthy/falsy values.

Hey @busterc: we started a fork here we're actively maintaining. We'd happily accept this pull request.