Add support of TLS connections

[Onlinehead]

Just little change about support of TLS connections which sometimes useful.
Here is example of using with TLS:

amqp_url := "amqps://guest:guest@127.0.0.1:5671/"
cert, err := tls.LoadX509KeyPair("cert.pem", "key.pem")
tls_config := tls.Config{
			Certificates: []tls.Certificate{cert},
			InsecureSkipVerify: true}
cli := cony.NewClient(
		cony.URL(amqp_url),
		cony.Backoff(cony.DefaultBackoff),
		cony.TLS(&tls_config),
	)

[kron4eg]

@Onlinehead hello, and thank you for your PR!

I want to suggest couple of things. Please take a look at how amqp.Dial() and amqp.DialTLS() are implemented. They both use the same amqp.DialConfig(), which call actual dial function, and it can handle amqps:// scheme automatically, so there is no need in

if c.tlsConf != nil {

So what we can do instead of cony.TLS() function is cony.Config(), and pass initialized amqp.Config in it, which should be used in amqp.DialConfig replacing amqp.Dial in cony source.

Thank you!

[Onlinehead]

@kron4eg Thanks for your tips.
I changed code for using DialConfig and yes, that is pretty better way:)
About checks, that is so strange, because on my PC checks passed without error:

PASS
ok      github.com/onlinehead/cony  0.015s

[kron4eg]

I wander if it's necessary to provide default Heartbeat in case it's 0, like in original amqp.Dial()... It's very easy to forget about it and get strange disconnects.

[kron4eg]

LGTM 👍