livemedia-creator: add some error checking

- Add a check to livemedia-creator for /usr/bin/virt-install (#841566)
- Suggest the correct package for livemedia-creator's libvirt (#841552)
- Add to list of packages needed to build a livemedia-creator iso (#841594)

README.livemedia-creator

@@ -108,7 +108,7 @@ passwd -d root > /dev/null
 cat /dev/null > /dev/fstab
 
 11. Don't delete initramfs files from /boot in %post
-12. Have grub-efi in the package list
+12. Have grub-efi, memtest86+ and syslinux in the package list
 
 One drawback to using virt-install is that it pulls the packages from
 the repo each time you run it. To speed things up you either need a local

docs/fedora-livemedia.ks

@@ -3,7 +3,7 @@ sshpw --username=root --plaintext randOmStrinGhERE
 # Firewall configuration
 firewall --enabled --service=mdns
 # Use network installation
-url --url="http://dl.fedoraproject.org/pub/fedora/linux/development/17/x86_64/os/"
+url --url="http://dl.fedoraproject.org/pub/fedora/linux/development/18/x86_64/os/"
 
 # X Window System configuration information
 xconfig  --startxonboot

src/sbin/livemedia-creator

@@ -673,7 +673,11 @@ if __name__ == '__main__':
         sys.exit(1)
 
     if not opts.no_virt and not libvirt:
-        log.error("virt-install requires libvirt to be installed.")
+        log.error("virt-install requires libvirt-python to be installed.")
+        sys.exit(1)
+
+    if not opts.no_virt and not os.path.exists("/usr/bin/virt-install"):
+        log.error("virt-install requires python-virtinst to be installed.")
         sys.exit(1)
 
     if opts.no_virt and not os.path.exists("/usr/sbin/anaconda"):