JH 3 - N2 modifications to support Identity

This completes N2 changes to support ASP.NET Identity:
a) N2 user management pages may be replaced with custom implementations
b) all calls to classic membership are wrapped.
Default implementation supports classic-membership to assure no breaking changes are introduced
(please review JH 3.4 commit).
TODO: wrap n2 installation logics! (It is still unchanged - and classic-membership specific).