Description of problem:
Vagrant up fails with error if virtualization is disabled in BIOS


Steps to Reproduce:
Disable virtualization in BIOS setting and try "vagrant up"

Additional info:

### Vagrant up fails if Virtualization is disabled by the bios.
--------------------------------------------------------------------------
[pavan@dhcp35-202 rhel-ose]$ vagrant up
Bringing machine 'default' up with 'libvirt' provider...
==> default: Creating image (snapshot of base box volume).
==> default: Creating domain with the following settings...
==> default:  -- Name:              rhel-ose_default
==> default:  -- Domain type:       kvm
==> default:  -- Cpus:              2
==> default:  -- Memory:            1024M
==> default:  -- Management MAC:    
==> default:  -- Loader:            
==> default:  -- Base box:          cdkv2
==> default:  -- Storage pool:      default
==> default:  -- Image:             /var/lib/libvirt/images/rhel-ose_default.img (41G)
==> default:  -- Volume Cache:      default
==> default:  -- Kernel:            
==> default:  -- Initrd:            
==> default:  -- Graphics Type:     vnc
==> default:  -- Graphics Port:     5900
==> default:  -- Graphics IP:       127.0.0.1
==> default:  -- Graphics Password: Not defined
==> default:  -- Video Type:        cirrus
==> default:  -- Video VRAM:        9216
==> default:  -- Keymap:            en-us
==> default:  -- TPM Path:          
==> default:  -- INPUT:             type=mouse, bus=ps2
==> default:  -- Command line : 
Error while creating domain: Error saving the server: Call to virDomainDefineXML failed: invalid argument: could not find capabilities for domaintype=kvm 
--------------------------------------------------------------------------


We can confirm that CPU actually supports virtualization but is disabled in BIOS by running virt-host-validate on a Fedora system:
--------------------------------------------------------------------------
[root@dhcp35-202 ~]# virt-host-validate 
  QEMU: Checking for hardware virtualization                                 : PASS
  QEMU: Checking if device /dev/kvm exists                                   : FAIL (Check that the 'kvm-intel' or 'kvm-amd' modules are loaded & the BIOS has enabled virtualization)
  QEMU: Checking if device /dev/vhost-net exists                             : PASS
  QEMU: Checking if device /dev/net/tun exists                               : PASS
   LXC: Checking for Linux >= 2.6.26                                         : PASS
--------------------------------------------------------------------------


### Need to enable virtualization for ex. Intel VT(if using Intel processor) in the bios setting. It would be better to document this error and steps to enable virtualization in the bios setting, maybe in the troubleshooting section of the CDK install guide.