templatize the envvars file

The envvars file (typically installed into /etc/apache2/envvars) sets some environment variables that are used by the init script.

It sets the user to run as, group, pidfile location, etc.

Previous versions of the cookbook didn't include this file, so the init system would be using the wrong pidfile location, for example, and wouldn't know how to stop/restart apache.

This version uses the same values that are used in the rest of the apache2 configuration.
first commit for apache 2.4 support, still need to test backwards compatibility
updated authors and reverted version (for now)
add back apache 2.2 SSLMutex directives
added authz_default -> authz_core backwards compatibility
typo for mod_wstunnel
fix merge fail: missing end in status.conf
minimize changes in brackets
minimize changes in brackets
minor cleanup
rubocop cleanup
more rubocop cleanup
fix a copyright typo
fix non-closing directory block directive
only load the mpm module on apache 2.4
use single quotes
fix indentation
Disable the other MPM modules when enabling one of them

If you don't disable the other modules first, apache complains that there's more than one MPM module enabled.
use ip addresses instead of hostnames for allow lists

In the Apache 2.4 beaches of some modules, "Require ip" is used, and that only works on ip addresses.

The choice is to either set the default attributes to IPs, change the modules to use "Require host", or split the allow lists into an ipaddress and hostname version so the user can specify both.

I've just changed the defaults to use IPs.
don't change the pidfile location for 2.2 as it breaks service restarts