Add handling of HTTP redirects

[matthewquinn]

When the Octiron store performs a request which responds with a 300 status code, if the response location is allowed in the store's configuration the redirect should be followed.

The Octiron store will have to support a new response state which points from the first response with the redirect status to the next response. This will provide getSelection() with the required information to follow the redirect and update subscribers.