Updating server dependancies. Also adding github.com/jaytaylor/html2text and gopkg.in/gomail.v2 (#5748)

vendor/github.com/miekg/dns/dnssec_keyscan.go

@@ -36,7 +36,7 @@ func (k *DNSKEY) ReadPrivateKey(q io.Reader, file string) (crypto.PrivateKey, er
 		return nil, ErrPrivKey
 	}
 	// TODO(mg): check if the pubkey matches the private key
-	algo, err := strconv.Atoi(strings.SplitN(m["algorithm"], " ", 2)[0])
+	algo, err := strconv.ParseUint(strings.SplitN(m["algorithm"], " ", 2)[0], 10, 8)
 	if err != nil {
 		return nil, ErrPrivKey
 	}