Remove last pieces of the flags system

The flags system was a well intentioned way to disable certain parts of the provisioning script from running. It quickly whittled back down to one flag, which controlled the WordPress unit tests. Rather than continuing to maintain this weird little `flags` directory, this commit removes that in favor of creating an empty `www/wordpress-unit-tests` directory to stop unit tests from being checked out or updated.

Closes #91
Change network check to ping 8.8.4.4 rather than 8.8.8.8

8.8.8.8 was not responding today, so using Google's primary DNS server instead.

See #107, a better solution is probably needed.