MvcSiteMapProvider does not respect AllowAnonymous with SecurityTrimmingEnabled in MVC4

Fixes #130.

Previously submitted under pull request #132.

I added the logic from v4, but it turns out it was not really necessary. Everything compiled fine for MVC2, but I couldn't get it running (before) because of configuration problems. I did test it under MVC2 again and everything is fine.

It is a real BEAR trying to get the MvcMusicStore to compile and run under MVC2, MVC3, and MVC4 because of all of the different places in the Web.config files and project file that need to be changed. I suggest going forward we use solution configurations for this so one IDE setting can be changed to get the whole solution to compile and run under a specific version. Then we can just use transformation to get the Web.config files into the proper state in each case. Or if there is a better option, I would like to hear it.