Various SDHP improvements

* `AppDomainAssemblyTypeScanner` scans bin paths for assemblies that references any Nancy assembly

* Razor will now add an assembly reference to all assemblies returned by `AppDomainAssemblyTypeScanner.Assemblies`

* Removed call to `AppDomainAssemblyTypeScanner.LoadAssembliesWithNancyReference` (formaly known as `LoadNancyAssemblies`) from the `NancyBootstrapperBase.Initialise` method since it's already peformed from the static ctor of `AppDomainAssemblyTypeScanner`