Numerous fixes

- Fix the SignOut() method to work as required.
- Add a Logout controller method that properly kills your
authentication.
- Add to OnAuthenticated to save the e-mail and id_token to a cookie in
all relevant locations.
- Add the NuGet .nuspec file and readme.txt so they can also be
community-modified. NOTE: You will need to update the file for the
proper build locations and to add the source code like I showed you.