Add model for Cisco small business switches

This new model should support Cisco Small Business 200, 300, 500, and ESW2 series switches. It appears [the same firmware][1] is used throughout.

[1]: http://www.cisco.com/c/en/us/support/switches/small-business-300-series-managed-switches/products-release-notes-list.html

I'm not sure what to name the model. I can't find a name for the operating system from any Cisco documentation. It's currently Cisco300 because I have a 300 series switch.


This model strips the extra '\r' on the first line at the beginning of a response.
```
"\r\n\r\r\n\r\n\r\nUser Name:"
"admin\r\n\rPassword:"
```

Closes #40.