Fix build when using go modules (#6)

vendor/github.com/go-openapi/swag/net.go

@@ -0,0 +1,24 @@
+package swag
+
+import (
+	"net"
+	"strconv"
+)
+
+// SplitHostPort splits a network address into a host and a port.
+// The port is -1 when there is no port to be found
+func SplitHostPort(addr string) (host string, port int, err error) {
+	h, p, err := net.SplitHostPort(addr)
+	if err != nil {
+		return "", -1, err
+	}
+	if p == "" {
+		return "", -1, &net.AddrError{Err: "missing port in address", Addr: addr}
+	}
+
+	pi, err := strconv.Atoi(p)
+	if err != nil {
+		return "", -1, err
+	}
+	return h, pi, nil
+}