[#35] network: Use AppendComponent() for TLS encapsulation

As advocated explicitly in https://github.com/multiformats/go-multiaddr/blob/master/v015-MIGRATION.md

Answering a question about safety:
AppendComponent() appends to `a.ma`` in place.
`a.ma` is created by FromString() function,
so there is only a single goroutine appending to it.
Thus, assuming `FromString()` itself is called from a single goroutine,
no data race is introduced.

Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>

pkg/network/address.go

@@ -66,7 +66,7 @@ func (a *Address) FromString(s string) error {
 		if err == nil {
 			a.ma, err = multiaddr.NewMultiaddr(s)
 			if err == nil && hasTLS {
-				a.ma = a.ma.Encapsulate(tls)
+				a.ma = a.ma.AppendComponent(tls)
 			}
 		}
 	}

pkg/network/tls.go

@@ -9,7 +9,7 @@ const (
 )
 
 // tls var is used for (un)wrapping other multiaddrs around TLS multiaddr.
-var tls, _ = multiaddr.NewMultiaddr("/" + tlsProtocolName)
+var tls, _ = multiaddr.NewComponent(tlsProtocolName, "")
 
 // IsTLSEnabled searches for wrapped TLS protocol in multiaddr.
 func (a Address) IsTLSEnabled() bool {