Allow changing TLS connection options in client

node v0.10 TLS validates server certificates by default, so allow for setting custom connection options (e. g. `ca` or `rejectUnauthorized`).

Quoting node's [changelog](https://github.com/joyent/node/blob/master/ChangeLog):

> 2012.09.17, Version 0.9.2 (Unstable)
> ...
> * tls, https: validate server certificate by default (Ben Noordhuis)