Account fixes

Bugfixes.
Removed some dependencies on Membership.
EditableRoles moved from N2 core to management, hopefully without any
breaking changes.
N2.Security.Aspnet.Identity

Optional package (Visual Studio 2013, MVC 5)
Replaces N2 Membership subsystem.
Proto.N2Dinamico.OwinIdentity

Demo application, demonstrates N2 Dinamico on ASP.NET MVC 5 /
Aspnet.Identity.