remove unused code

Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
introduce base_handler_class

To make the framework more generic. The final plan is to move the
generic server code to package pve-common.

Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>
HTTPServer: correctly unescape url
PVE::REST - always add method info to result

This is usefule for result formaters.
allow to return HTTP::Response object from format_response_data()

A formater can generate HTTP redirect now.
add generic formater support
move formater registration to HTTPServer
fix typo
split out formatter code
include bootstrap html framework
improve copyright file
really install bootstrap files
new html formatter PVE::API2::Formatter::HTML

This one provides a login page and uses bootstrap for html.
Formatter/HTML: add method description
bump version to 3.2-5