Fixed a bug where a redirect was not happening.

The users were not properly being redirected after then authorized the shim to read from an external data source. This should be fixed by returning a 302 and having the redirect URL set as the Location header.

Closes #10
Updated the authorization flow.

There were some issues with how redirect URLs were being built and the external authorization flow as well. This has been updated to make it easier for implementors to create their own ExternalAuthorizationInformation objects. The OAuth v1 implementation has been updated as well.

References #8