feat(proxy): add https proxy support #293

`proxies` entries in the config file will be examined for 'http/s'. In the case of https the `target.https` of https-proxy will be set to true. 

The default port for each protocol (80/443) will also be used if no port is specified in the url.

A config option `validateSsl` (default:true ie invalid SSL certs generate an error) that sets the TLS `rejectUnathorized`. Allow the use of self signed certs.