Fixes #130, respect AllowAnonymous attribute when it is used. Also added AllowAnonymous attribute to XmlSiteMapController so it will allow search engines if a global AuthorizeAttribute is used.
Changed compilation constant logic in MvcSiteMapProvider.csproj to match that in v4.
Merge pull request #145 from NightOwl888/v3-allow-anonymous-patch

MvcSiteMapProvider does not respect AllowAnonymous with SecurityTrimmingEnabled in MVC4