Added #vendor method to host spec

I wasn't really sure how to go about asking for this, so I wrote what I think is the start to a spec for the feature.  I would like to be able to pull the vendor information so I do not need to do mac address look ups in some other way.

__For example, please view:__
*  method on line 43 (disect_vendor_scan)
*  test line 78 (test_disect_vendor_scan).
*  [In this file](https://github.com/BrentonEarl/sleuth-sentry/blob/disect_scan_output/test/disect_test.rb)