shell: Make real dashboard server links

This makes us able to open them in new tabs, or new windows, middle
click them, drag them etc.

Closes #1575
Reviewed-by: Marius Vollmer <marius.vollmer@redhat.com>
websocket: Allow parsing the HTTP version from responses
bridge: Implement keep alives for http-stream1 channels

We keep one connection around for 10 seconds in case another request
comes for the same thing.

In addition callers can specify a "connection" identifier which
allows them to reuse a specific connection if it is still open. This
is useful for strange connection based authentication schemes.

Closes #1579
Fixes #1570