[Feature] Custom MembershipProvider

[JonnySchnittger]

Integrating a custom membership provider (http://msdn.microsoft.com/en-us/library/system.web.security.membershipprovider(v=vs.110).aspx) or extending the default SimpleMembershipProvider (http://msdn.microsoft.com/en-us/library/webmatrix.webdata.simplemembershipprovider(v=vs.111).aspx) to allow the association of a theme to a specific user would greatly improve the engines utility and clean up the querystring.

[AaronLayton]

@JonnySchnittger I think if the initial idea #8 gets implemented correctly then this should be an easy addition, but maybe something that we just give an example of how to do using ViewEnginePlus