Implemented modular code structure

Refactored repository into kaya-core and kaya-rsgi packages

example/hello.py

@@ -1,15 +1,6 @@
-from kaya import KayaApp, HttpContext, HttpMethod, WebSocket
+from kaya.core import KayaApp, HttpContext, HttpMethod, WebSocket
 from typing import List
 
-class Hello(KayaApp):
-    pass
-
-    # async def handle_request(self, ctx: HttpContext) -> None:
-    #     async for chunk in ctx.request_body:
-    #         print(chunk.decode())
-    #     await ctx.send_str(200, 'Hello World')
-
-
 app = KayaApp()
 
 
@@ -53,4 +44,4 @@ async def echo(ws: WebSocket) -> None:
         elif msg.kind == 'binary':
             data = msg.data
             assert isinstance(data, bytes)
-            await ws.send_bytes(data)
+            await ws.send_bytes(data)