Fix ReflectionDiscoverableCollection locking files

When ReflectionDiscoverableCollection loads assemblies to discover types it locks the assemblies.

This causes issues in ASP.NET applications because it was loading the assemblies from the BaseDirectory of the appdomain and not from the shadow copy directory being used by the ASP.NET application.
Merge pull request #222 from joshperry/shadowcopy

Fix ReflectionDiscoverableCollection locking files