ETag-based caching

[jace]

Coaster needs a decorator that supports caching with the ETag header. A regular Flask-Cache cache decorator will save server processing time, but not bandwidth consumption for the client.

This example is a good starting point. It needs a hashing algorithm for the ETag value (Blake2b is suitable), a cache-busting mechanism to allow longer timeout periods, and support for If-None-Match and If-Match in POST requests.