virt-sysprep: Switch to using guestmount, add more features.

This switches virt-sysprep to use guestmount instead of guestfish.
This makes the script a little bit easier to modify for sysadmins.

This commit also adds:

 - dhcp-client-state
 - dhcp-server-state
 - logfiles
 - random-seed
 - smolt-uuid
 - yum-uuid

SELinux relabelling, and a section on security in the manual page.

README

@@ -134,6 +134,12 @@ To build the Perl tools:
 
 - perl-libintl for translating perl code (optional)
 
+To run virt-sysprep:
+
+- xmlstarlet (optional)
+
+- virt-sysprep also requires FUSE support since it uses guestmount
+
 
 Building
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