Fixed #831 by fixing a typo in the test configuration.

When I encountered #831, it was because I had changed my `hostname` setting
in  `lib/environments/local.js` from `localhost` to a VMWare intranet IP
so I could  test the backpack from an IE8 VM. The test configuration was
overriding the `host` setting instead of the `hostname` setting, which was
the wrong one to override--hence the app harness was still going back to
the current config when resolving absolute URLs, instead of the test one.
Merge pull request #832 from toolness/issue-831

Fixed #831 by fixing a typo in the test configuration.