Features:

 * amend configuration with comments
 * drop obsolete comments from Apache copy
 * remove not needed whitespaces
 * use indentation for conditionals in Jinja2

Where applicable simplify Jinja2 templates by removing Caddy-TODO
and fill or update TODO.rst.

Therte is no need to control whitespace adding by Jijna2 and dropping it
simplifies the templates.

It will allow to take better control over generated configuration files.

The goal is to drop slapos.cookbook:erp5.test

No need for a recipe to do a bit of url parsing and generating 2 wrappers.
Also, drop unused & empty "host-common" section.

- stack/erp5: Add path to all binary links in PATH
- stack/erp5: Add single quotation marks to not break parameters in many lines
- stack/erp5: Fix path to avoid one section to overwrite the file from another section
- stack/erp5: pass cloudooo host instead of the IP address. The IP address and cloudooo hostname are well in $SLAPPART/etc/hosts
- stack/erp5: Use use-ipv6 instance parameter to control where caucased listens when locally deployed.
  Drop incomplete 6tunnel usage on balancer toward zopes.

Tests are somehow happy test_result_module/20180626-62AD32BB test_result_module/20180626-70AC16FA

If no objections I would like to merge tomorrow but feel free to press merge for me :)

The goal is rebase !318 to fix the conflict and merge after tomorrow.

/cc @rafael @vpelletier 

/reviewed-on !347

While reading templates/cached-virtualhost.conf.in it seems, that
SSL-enabled host shall be exposed, but this is not true -- it is
connecting to SSL backend, but listening on non-SSL.

In order to stabilise this add assertsion to test_enable_cache
which access cached ports directly and show its functionality, thus
resolving added TODO.

Whenever there is a problem while building software or instantiation,
emit verbose information for further analysis.

apache-frontend supports correctly ssl_proxy_ca_crt for ssl-proxy-verify,
thus show it in test, still keeping expected 501 reply for caddy-frontend.

The schema shall be https, not http. It got undetected, as caddy-frontend
dies really fast with 501, while apache-frontend is able to communicate
with the backend.

As result of copying nginx configuration from apache-frontend, it was
NOT adapted to Caddy behaviour. Thus make it so, with catch-all apporach
as in Caddy.

Also update test data, as access logs for main nginx instance is now available.

As sources URL depends on the branch, update it to correct one.

 * add switch-softwaretype from review
 * add graceful scripts improvement
 * inform about certificates in tests with explanation
 * add about improving test infrastructure

It is superseded by caddy-frontend

stack for Caddy software will appear later.

As there is some kind of "collision" with request, allow to override
parameters.

Treat `<key>` as default and overwrite it with `frontend-config-<num>-<key>`,
instead of having the global `<key>` always passed to slaves.

This allows to request the partition with:

  monitor-httpd-frontend=12345
  -frontend-config-1-monitor-httpd-frontend=9876
  -frontend-config-1-monitor-httpd-frontend=8765

jinja2 template is required, as some paramters might come from the network.

Removing 'secure' from cookie send by backend is plain wrong.

It is used internally for communication between backend and the server.

mpm-watchdog promise is not applicable for Caddy.

404 is served with notfound.html

Those kept are backward compatibility variables from the request.

Caddy is able to bind only to all or one interface
( https://github.com/mholt/caddy/issues/864 )

By using 6tunnel this limitation is workarounded, and in the result listen on IPv6.

Also drop needless "ipv6" keys across configuration.

As the the feature ssl_proxy_ca_crt is not implemented serve immediately
501 Not Implemented.

As the the feature ssl_proxy_ca_crt is not implemented serve immediately
501 Not Implemented.