Add a box definition for Fedora 20 on vagrant-kvm.
Add a box definition for CentOS 6 on vagrant-kvm.
Add a box definition for Ubuntu 14.04 "Trusty Tahr" Beta 2 on vagrant-kvm.
Set UseDNS no for sshd on Arch Linux.
Set UseDNS no for sshd or Fedora 20.