Start ssh daemon after other scripts are run, to avoid premature shutdown

Start ssh daemon after all other scripts are run, to avoid premature shutdown (floppy/zz-net-start-sshd.cmd)
Fixes #33
Added a `ping` at the end of `provisioner.bat` to force display of script output. Otherwise, we see

````
==> vmware: Provisioning with shell script: script/vagrant.bat
    vmware: ==> Installing vagrant public key
    vmware: ==> Disabling vagrant account password expiration
    vmware: Updating property(s) of '\\WINDOWS-6VV5B4H\ROOT\CIMV2:Win32_UserAccount.Domain="WINDOWS-6VV5B4H",Name="vagrant"'
==> vmware: Provisioning with shell script: script/provisioner.bat
==> vmware: Provisioning with shell script: script/vmtools.bat
    vmware: ==> Downloadling http://downloads.sourceforge.net/sevenzip/7z922-x64.msi to C:\Users\vagrant\AppData\Local\Temp\7z922-x64.msi
    vmware: ==> Download complete
    vmware: ==> Installing 7zip from "C:\Users\vagrant\AppData\Local\Temp\7z922-x64.msi"
    vmware: ==> Uninstalling 7zip
==> vmware: Provisioning with shell script: C:\cygwin\tmp\packer-shell086829155
````