GH-20: read /etc/environment to make FACTER_* env vars available on reboot

This fixes the problem of FACTER_* variables not being available to
Puppet facter when rc.local is run after a machine reboot.  If the
FACTER_* variables are missing, Puppet will not be able to update the
/etc/hosts and /etc/resolv.conf files correctly, which will prevent
deployed machines from communicating with each other (because hostnames
cannot be resolved).