the previous fix for #4465 assumed that the NetworkManager takes care of updating /etc/hosts with
the new hostname, but testing shows it doesn't. This change ensures that the change is always added
to /etc/hosts when the name changes.
This PR sets the active hostname back to the name specified in the Vagrantfile (fqdn) and updates the unit tests.
Setting it to the short name causes loads of problems while configuring the system. I've had issues with sudoers hostname matching, Weblogic certificate generation and a few others. Even if I changed all of the Chef recipes, the fqdn is set in /etc/sysconfig/network so the active hostname will switch to the fqdn after a reboot.