ConditionalHeaders feature adds ability to avoid sending content if client already has same content. It does so by
checking ETag or LastModified properties of the Resource or FinalContent being sent and comparing these
properties to what client indicates it is having. If conditions allow it entire content is not sent and
"304 Not Modified" response is sent instead.
install(ConditionalHeaders)This feature doesn't have any configuration object, but configuration script is executed if present.
Version interface implementations are attached to Resource instances, and you can return custom implementations
with your own logic. Please note that FinalContent is only checked for ETag and LastModified headers.