Changed specs to use httpstat.us for real requests.
Revert "Merge pull request #300 from tbeauvais/httpclient_thread_safe"

This reverts commit 04d5fe1d71d795528297b37eb4498fe7c0c344c3, reversing
changes made to be0df72566e4887d5224fe1abb5f559a58dd3f98.