Scan only relevant (non skipped) assemblies
FinalizeSetup point, to make "stuff" immutable
Support controllers under any namespace
support customizing controller discovery
support customizing skipped assemblies
support customizing multiple controllers with the same name under different namespaces and assemblies
support controller ambiguity detection
* Paths rooted by a leading slash (e.g. /foo) are correctly resolved by the
PhysicalFileSystem. This change is an experiment to determine if we can
get away with not having virtual paths in WebFx.
* Additionally removing types (MetadataVirtualPathViewFactory,
VirtualPathAttribute) that are currently unused.