Loops and HTTP control server rework (#308)

- CRUD REST HTTP server
- `/v1` HTTP server prefix
- Retrocompatible with older routes (redirects to v1 or handles the requests directly)
- DNS, Updater and Openvpn refactored to have a REST-like state with new methods to change their states synchronously
- Openvpn, Unbound and Updater status, see #287

internal/models/alias.go

@@ -20,8 +20,14 @@ type (
 	VPNProvider string
 	// NetworkProtocol contains the network protocol to be used to communicate with the VPN servers.
 	NetworkProtocol string
+	// Loop status such as stopped or running.
+	LoopStatus string
 )
 
+func (ls LoopStatus) String() string {
+	return string(ls)
+}
+
 func marshalJSONString(s string) (data []byte, err error) {
 	return []byte(fmt.Sprintf("%q", s)), nil
 }