Revert "Merge pull request #15 from praeclarum/master"

This reverts commit 339abae05b64d60aec83b06275da55eac0f99822, reversing
changes made to b839665176c64659a84442a6f3567e98a61d19a8.

The new API to restore cookies is rather redundant, since if you already
have an Account, you'd use it to make requests instead of authorizing
again.
Restore early redirect detection changes
Add ClearCookiesBeforeLogin and ClearCookies()

The general assumption is that the user is showing the login UI to login a
new user. With that, automatically clearing the cookies before showing the
UI works to ensure they're not getting logged back into the user they're
already logged in as when switching accounts.

However, in situations where XA is only half of the story (like Azure
Mobile Services), it's useful to just keep the cookies but have a way to
clear them manually. So, in order to maintain current behavior,
ClearCookiesBeforeLogin was added and defaulted to true.