Preserve the UUIDs and the Labels in host bundling

When bundling a host, make sure that the UUIDs and the Labels of the
original file systems are preserved.
docs: Update the installation instructions

 * Add instructions for CentOS 7
 * Use curl in favor of wget on Fedora and CentOS systems.
Detect more Ubuntu variants

Detect Kubuntu, Lubuntu and Xubuntu
docs: Add a troubleshooting section

Populate this section with instructions on how to troubleshoot
libguestfs's launch failures.
windows: Remove the format=raw attribute from kvm

Do not use format=raw in the -drive option of KVM when booting the
Windows VM. The format could also be qcow2 if the original input media
is a regular file.
windows: Loosen up the 'shrink QUERYMAX' regexp

Do not search for specific words in it. The messages may be in a
language other than English. Focus on the Numbers.
Update version files and ChangeLog for 0.7.1
Merge pull request #26 from skalkoto/hotfix-0.7.1

Bug fixes and documentation updates
Merge branch 'origin/master' into develop

Bump version to 0.7.1next