IPVanish support (#475)

- Fix #410 and #416

internal/updater/providers/ipvanish/sort.go

@@ -0,0 +1,19 @@
+package ipvanish
+
+import (
+	"sort"
+
+	"github.com/qdm12/gluetun/internal/models"
+)
+
+func sortServers(servers []models.IpvanishServer) {
+	sort.Slice(servers, func(i, j int) bool {
+		if servers[i].Country == servers[j].Country {
+			if servers[i].City == servers[j].City {
+				return servers[i].Hostname < servers[j].Hostname
+			}
+			return servers[i].City < servers[j].City
+		}
+		return servers[i].Country < servers[j].Country
+	})
+}