Credentials extraction mechanism should use ICredentialsFactory

[Laurens Van Houtven]

The credential extraction interface in lp:~lvh/txoauth/client-credential-extraction, while functional, doesn't do the right Twisted thing. Instead, it should provide you with an implementation of ICredentialsFactory.

http://twistedmatrix.com/documents/10.0.0/api/twisted.web.iweb.ICredentialFactory.html

[Laurens Van Houtven (lvh)]

The reason we want all things that turn t.w.iweb.Request into ICredentials to use ICredentialsFactory is so we can use HTTPAuthSessionWrapper as described here:

http://jcalderone.livejournal.com/53074.html

[Laurens Van Houtven (lvh)]

This will affect the tests, since they will now need to raise LoginFailed as opposed to TypeError.