File-based response support & static server

- Clean up UniversalPath implementation
    - Use Readable/Writable types correctly for stream methods
    - Add .list() methods for getting child files

- Make Response body specify explicit types and support
  writing Readable streams to the body

- Create a static file server that supports directory listing

src/index.ts

@@ -43,6 +43,7 @@ export * from './http/response/ResponseFactory'
 export * from './http/response/StringResponseFactory'
 export * from './http/response/TemporaryRedirectResponseFactory'
 export * from './http/response/ViewResponseFactory'
+export * from './http/response/FileResponseFactory'
 
 export * from './http/routing/ActivatedRoute'
 export * from './http/routing/Route'
@@ -57,6 +58,8 @@ export * from './http/session/MemorySession'
 
 export * from './http/Controller'
 
+export * from './http/servers/static'
+
 export * from './service/Canonical'
 export * from './service/CanonicalInstantiable'
 export * from './service/CanonicalRecursive'