Register again after short delay if registration does not work

In my setup the registration on the RegistryServer does not always work the first time. However, if noticed, that retrying a second time makes the registration happen as expected.

The following code changes check if calling `register` on the `TCPRegistryClient` or `UDPRegistryClient` was successful. If it was not, than another registration attempt is made after 1 s of delay.