Description of problem:
xenguest-install creates "block:" types instead of "phy:" for the "disk=" line
in a xen guest config file if the disk image is on a block device.  This results
in a non-bootable guest: it installs OK, but cannot be run thereafter.

Version-Release number of selected component (if applicable):
python-xeninst-0.93.0-1

How reproducible:
100%

Steps to Reproduce:
1. Install to any block device
2. Try to run the resulting guest
3. Inspect the /etc/xen config file
  
Actual results:
# xm create -c rhel5
Using config file "/etc/xen/rhel5".
Going to boot Red Hat Enterprise Linux Server (2.6.18-1.2704.el5xen)
  kernel: /vmlinuz-2.6.18-1.2704.el5xen
  initrd: /initrd-2.6.18-1.2704.el5xen.img
Error: Device 51712 (vbd) could not be connected. Hotplug scripts not working.

Config file contains "disk = [ 'block:$DEV,xvda,w', ]"

Expected results:
Guest should boot
Config file should contain "disk = [ 'phy:$DEV,xvda,w', ]"