Setting up multiple apache2 instances on Ubuntu 16.04

PHP handling on apache is done via modules of one sort or another, and running multiple version is problematic on a single instance. The solution is to run two instances of apache on the same machine. This allows one instance to run PHP 7 (the default on 16.04), and another can run PHP 5. Since normal http/https is on ports 80 and 443, the second instance will run on ports 81 and 444. Since it is running on the same machine, all file system and database access is the exact same.

All the commands herein have to be run as root, or with sudo prefixed to the command.

1. Read /usr/share/doc/apache2/README.multiple-instances

2. Run sh ./setup-instance php5 from /usr/share/doc/apache2/examples, where php5 is the suffix for the second site; all commands for the second site will have that suffix. This will keep all of the same configuration for all sites on the new instance, including SSL certif