Incorrect dll version(1.1.0 instead of 2.1.0)

[aliluyko89]

After installation of package using nuget and running following command Install-Package FluentNHibernate -Version 2.1.0
I noticed that installed lib has version 1.1.0 instead of 2.1.0
I marked all lib versions on screen

[michalkowal]

Pull Request ready for review: #396