Asgi-proxy-lib

- All proxied requests now use `accept-encoding: identity` in the request header to the backend, to avoid any problems caused by compressed content. [9](https://github.com/simonw/asgi-proxy-lib/issues/9)
- Proxied requests no longer have a default timeout of 5 seconds, which makes streaming APIs less likely to error. This can be changed using the `timout=` parameter or on the CLI with the new `--timeout 3` option, which takes a floating point number of seconds. [10](https://github.com/simonw/asgi-proxy-lib/issues/10)

- First working version. Use the `app = asgi_proxy("https://url-goes-here")` function to create an ASGI application that proxies all incoming requests to the specified backend. [#1](https://github.com/simonw/asgi-proxy/issues/1)