Add a separate domzero user

This user will have the automated key updater script, dom0 should use
this account to log in to the appliance.
Create ssh related files
XVA creator requires a basename to be specified

This way I can build different xvas for different branches.
Fix typo
Fix missing home from path, add debug, fix typo
use sudo for xenstore
Merge pull request #15 from matelakat/separate-account-for-domzero

Separate account for domzero