Improvement: Update context when updating account

[jwillmer]

I noticed that my context does not reflect the changes when I update my account details (email). I think it would be good if the context applies the changes so that I do not need to recreate it.

  ..
  await UpdateAccount(server, accountKey);
  return new AcmeContext(server, accountKey);
}  

/// <summary>
/// Update account to agree to terms in case they changed.
/// </summary>
/// <remarks>Context is not returned since it needs to be recreated in order to reflect the changes.</remarks>
/// <param name="server">Server URL</param>
/// <param name="accountKey">Certificate Key</param>
/// <returns></returns>
private async Task UpdateAccount(Uri server, IKey accountKey)
{
    var acme = new AcmeContext(server, accountKey);
    var account = await acme.Account();
    await account.Update(new[] { $"mailto:info@{DomainName}" }, true);
}