Maintainer required (again)

[leotsarev]

Tonight mailgun blocked my account without any warning. Even if they unblock me, it will push migration out of mailgun to Yandex Postbox higher in my backlog.

There is no hard feelings, but it's unlikely I'll mantain mailgun_csharp in near future.

Please consider migration to another client or forking. If mantainer won't come up or @bringking say otherwise, I'll unlist nuget project.