public void Register_GetByKey_Delete()
        {
            var email = Guid.NewGuid().ToString("N") + "@somewhere.com";
            var repos = new RavenDbAccountRepository(_session);
            var account = new MembershipAccount
                              {
                                  Email = email,
                                  UserName = email,
                                  Password = "******",
                                  ProviderUserKey = "ten"
                              };

            repos.Register(account);
            _session.SaveChanges();

            var user = repos.GetByProviderKey("ten");
            Assert.NotNull(user);

            repos.Delete(email, true);
            _session.SaveChanges();
        }