redirect of base_url should be sticky

[jeremyandrews]

Some websites use multiple domains to serve traffic, redirecting depending on the user's roll. For this reason, Goose needs to respect a redirect of the base_url and subsequent paths should be built from the redirect domain.

For example, if the base_url (ie --host) is set to foo.example.com and the load test requests /login, thereby loading http://foo.example.com/login and this request gets redirected to http://foo-secure.example.com/, subsequent requests made by this client need to be against the new foo-secure.example.com domain. (Further, if the base_url is again redirected, such as when loading http://foo-secure.example.com/logout, the client should again follow for subsequent requests, perhaps in this case back to foo.example.com.)

Load tests can also requests absolute URLs, and if these URLs are redirected it should not affect the base_url of the load test. For example, if foo.example.com is the base url, and the load test requests http://bar.example.com and gets redirected to http://other.example.com subsequent relative requests would still be made against foo.example.com.

If the load test requests