Added option for allowing self-signed certificate

[adam-golab]

Currently, the attempt to connect to the WebSocket server encrypted with self-signed certificate causes an error:

Error: self signed certificate

This pull request fixes it by adding -a (--allow-unauthorized) flag.

It will be useful for testing secured WebSocket servers during the development process.

[TheWildHorse]

Brilliant! Please merge this! :)

[js-kyle]

This would be very helpful