Wizard: Don't fully-qualify paths if not needed

'service' is in /sbin on Fedora, but on Ubuntu it's
in /usr/sbin.   Both directories should be in the user's
PATH, so just naming the executable should work in both
cases.

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Wizard: Disable xend on Debian-based distributions

Signed-off-by: Euan Harris <euan.harris@citrix.com>
Merge branch 'debian' of git://github.com/euanh/xenserver-install-wizard

Signed-off-by: David Scott <dave.scott@eu.citrix.com>

Conflicts:
	xapi.py
	xenserver-install-wizard.py