Http Server: Change the Swagger GUI to / instead of /ui

This patch is under the mgmt repository and it address:
https://github.com/cloudius-systems/mgmt/issues/39

When connecting to the http server, it is more common to connect to the
GUI as:
http://192.168.122.89:8000/

To support that the rule that matches the ui was moved to be the last
rule (with the lowest priority) and it is mapped to anything (i.e. the
empty string)

A rule was added to match the index.html in the root

Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>