Completely remove the version option

There is no real need to make the version configurable
since the git commit and the build date both are equally
important to the user.

The output of ECMD version looks now like this:

```
➜  ~  telnet 192.168.0.89 2701
Trying 192.168.0.89...
Connected to 192.168.0.89.
Escape character is '^]'.
version
Ethersex 361998b build date: Feb 11 2014 17:44:30
```