This fix changes the model for error messaging in antiforgery. Now only
the token store will report a detailed error message including the names
of form field and cookie. Other components will give more generic errors
and assume that this was handled by the token store.
This way you still see an error if the user creates a token store that
doesn't throw, but it's a generic error that doesn't give incorrect
information.
Doug Bunting
Pranav K
ryanbrandenburg
Chris R
Hao Kung
Ryan Nowak