Conflicts:
	software/ajaxplorer/software.cfg

Fixes "key ipv4_set slap-configuration:ipv4" referencing a non-existing
section (woops, copy/paste...).

Also, update documentation to state that web-checker can be disabled
altogether and that frontend-url is optional (it has a working default
value).
Also, provide replacements in frontend-url for easier configuration.
Also, stop depending on slap-network-information magical section.

Develop is bad anyway, but at least this fixes varnish software release in
master branch.