Synnefo

Auth providers improvements

- Enrich login/logout messages.
- Clear unverified accounts when user adds the same third party account
to an existing account.
- Other minor improvements.

Various auth providers fixes/improvements

- Handle invalid login after auth method add request
- Fix auth method add for unauthenticated users
- Third party auth providers helper methods in astakos.im.target module
- Provider login url template tag that handles code,key,next url params

Auth providers fixes

handle is_available_for_{create, add}