Introduces scan predicate for resource texts

The default implementation will scan all assemblies, that has a
reference to another assembly which has a name that begins with
Nancy.
Added more ignored assemblies
Renamed IAssemblyProvider

Changed it back to IResourceAssemblyProvider and made the
default implementation use the AppDomainAssemblyTypeScanner and
its ignore list.
Merge pull request #890 from thecodejunkie/resourcescanningconvention

Resource scanning convention