riemannc: fix --tcp and --udp options

The first commit fixes the --tcp and --udp options to riemannc since these options don't expect an argument. With the existing code a call like
```
riemannc --udp --host test
```
would fail because "--host" would be evaluated as the argument of the "--udp" option.

The second commit adds the --tcp and --udp options to the riemannc_usage() output.