Fix. rise error when receive untagged response with one token.

For example
```
CLI SEND: 0.001251258888515914 LOGOUT
CLI RECV: * BYE
CLI RECV: 0.001251258888515914 OK LOGOUT completed
```
In that case `* BYE` response causes error.
Merge pull request #3 from moteus/moteus-fix-response-with-one-token

Fix. rise error when receive untagged response with one token.