GetLoginRequestUri Method with optional NameValueCollection parameter and default access_type=offline in GoogleClient to have refresh_token

[Sbaia]

GetLoginRequestUri Method with optional NameValueCollection parameter for add query string parameters in uri.

Added default queryString parameter access_type=offline in GoogleClient, to take refresh_token from googleauth api, that otherwise is not returned.

Added OAuth.pfx signature with OAuth2 password

[niemyjski]

Hello,

Can you please make the requested changes.