make spec not dependent on network conditions

fixes #66

on a host system that resolves unknown domain names to a "helpful" search, this test will fail because there will never be a socket error. This change fixes that.

![screen shot 2014-08-08 at 11 26 40 am](https://cloud.githubusercontent.com/assets/6097/3858698/7eccddee-1f10-11e4-87fb-c946c5ce1f09.png)
![screen shot 2014-08-08 at 11 27 11 am](https://cloud.githubusercontent.com/assets/6097/3858699/7ed61eea-1f10-11e4-8896-2e01412ccc27.png)