* Makes more sense to parse the host only once instead of for each path.
* Allows proper handling of: If the host is not a valid host on the server,
the response MUST be a 400 (Bad Request) error.
We need an init function in order to process upgrade instructions
for protocols like WebSockets, but also to request an active receive
mode for long-polling connections, both of which will be implemented
at a later time.
