This includes a new directory listing template which was originally
from the Caddy project (used with permission and copyright attribution).
This is used whenever we serve directory listings so `rclone serve
http`, `rclone serve webdav` and `rclone rcd --rc-serve`
This also modifies the tests so they work with the original template which
is easier to debug.
Tests have been randomly failing with messages like
listen tcp 127.0.0.1:51778: bind: address already in use
Rework all the test servers so they choose a random free port on
startup and use that for the tests to avoid.
The purpose of this is to make it easier to maintain and eventually to
allow the rclone backends to be re-used in other projects without
having to use the rclone configuration system.
The new code layout is documented in CONTRIBUTING.