xenapi - cleanup

Add error on unitialised variable to the scripts. This way some issues
were identified. Also modify README with fresh variables. The patch
includes:
 - Add SWIFT_HASH to the README
 - Add XENAPI_CONNECTION_URL to the README
 - Add VNCSERVER_PROXYCLIENT_ADDRESS to the README
 - Introduce UBUNTU_INST_IFACE which is the OpenStack VM interface used
   for the netinstall. It defaults to eth3. Previously this parameter
   was set by the combination of HOST_IP_IFACE and the undocumented
   NETINSTALL_IP
 - get rid of NETINSTALL_IP
 - xenrc includes CLEAN_TEMPLATES
 - xenrc no longer tries to change directory
 - remove chrooting from prepare_guest.sh (STAGING_DIR was always / )
 - remove DO_TGZ variable from prepare_guest.sh
 - use arguments to call prepare_guest.sh, instead of env vars
 - Fix backslash escaping in prepare_guest_template.sh

NOTE: networking is about to be addressed in a separate change.

Related to blueprint xenapi-devstack-cleanup

Change-Id: Ie9a75321c7f41cc9a0cc051398d1e6ec2c88adfa
diff --git a/tools/xen/scripts/install_ubuntu_template.sh b/tools/xen/scripts/install_ubuntu_template.sh
index 43b6dec..00cabb0 100755
--- a/tools/xen/scripts/install_ubuntu_template.sh
+++ b/tools/xen/scripts/install_ubuntu_template.sh
@@ -7,9 +7,8 @@
 # Based on a script by: David Markey <david.markey@citrix.com>
 #
 
-# Exit on errors
 set -o errexit
-# Echo commands
+set -o nounset
 set -o xtrace
 
 # This directory
@@ -54,11 +53,11 @@
 pvargs="-- quiet console=hvc0 partman/default_filesystem=ext3 \
 console-setup/ask_detect=false locale=${UBUNTU_INST_LOCALE} \
 keyboard-configuration/layoutcode=${UBUNTU_INST_KEYBOARD} \
-netcfg/choose_interface=${HOST_IP_IFACE} \
+netcfg/choose_interface=${UBUNTU_INST_IFACE} \
 netcfg/get_hostname=os netcfg/get_domain=os auto \
 url=${preseed_url}"
 
-if [ "$NETINSTALLIP" != "dhcp" ]; then
+if [ "$UBUNTU_INST_IP" != "dhcp" ]; then
     netcfgargs="netcfg/disable_autoconfig=true \
 netcfg/get_nameservers=${UBUNTU_INST_NAMESERVERS} \
 netcfg/get_ipaddress=${UBUNTU_INST_IP} \