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/xenrc b/tools/xen/xenrc
index e4d8ac9..1956623 100644
--- a/tools/xen/xenrc
+++ b/tools/xen/xenrc
@@ -8,6 +8,9 @@
 # Name of this guest
 GUEST_NAME=${GUEST_NAME:-DevStackOSDomU}
 
+# Template cleanup
+CLEAN_TEMPLATES=${CLEAN_TEMPLATES:-false}
+
 # Size of image
 VDI_MB=${VDI_MB:-5000}
 OSDOMU_MEM_MB=1024
@@ -19,7 +22,6 @@
 # Host Interface, i.e. the interface on the nova vm you want to expose the
 # services on. Usually eth2 (management network) or eth3 (public network) and
 # not eth0 (private network with XenServer host) or eth1 (VM traffic network)
-# This is also used as the interface for the Ubuntu install
 HOST_IP_IFACE=${HOST_IP_IFACE:-eth3}
 
 #
@@ -65,12 +67,11 @@
 UBUNTU_INST_REPOSITORY="http://archive.ubuntu.net/ubuntu"
 UBUNTU_INST_LOCALE="en_US"
 UBUNTU_INST_KEYBOARD="us"
-# network configuration for HOST_IP_IFACE during install
+# network configuration for ubuntu netinstall
+UBUNTU_INST_IFACE="eth3"
 UBUNTU_INST_IP="dhcp"
 UBUNTU_INST_NAMESERVERS=""
 UBUNTU_INST_NETMASK=""
 UBUNTU_INST_GATEWAY=""
 
-# Load stackrc defaults
-# then override with settings from localrc
-cd ../.. && source ./stackrc && cd $TOP_DIR
+source ../../stackrc