CMD list in version string corrected; matches parseCommand().

`parseCommand()` defines commands as:

```
R: READ_HEX
r: READ_BIN
W: WRITE_HEX
w: WRITE_BIN
V: VERSION
```

This patch fixes the command list advertised in the version string to match that list; `R,r,w,W,V`
Merge pull request #1 from pda/mkeller-version-string

CMD list in version string corrected; matches parseCommand().