Add protocol choice

Signed-off-by: John Else <john.else@citrix.com>
Add xenstore client

Signed-off-by: John Else <john.else@citrix.com>
stash

Signed-off-by: John Else <john.else@citrix.com>
Add test plugin

Signed-off-by: John Else <john.else@citrix.com>