Add a method to fix read permission on ISO files

When starting a virtual machine, libvirt changes the user:group of the disk
files to libvirt-qemu or qemu (depends on Linux distribution)
That way libvirt can work properly with those files.

But if the file does not have read permission, libvirt won't be able to
access them.

This patch adds a method to add read permission on files to avoiding
problems when starting a virtual machine.

Also remove useless imports from utils.py

Signed-off-by: ShaoHe Feng <shaohef@linux.vnet.ibm.com>
Signed-off-by: Aline Manera <alinefm@linux.vnet.ibm.com>
Signed-off-by: Royce Lv <lvroyce@linux.vnet.ibm.com>
Remove kvmusertests.py

As libvirt changes the user:group of disk files we don't need to probe
the username of qemu process
We just need to add read permission for those files as they already will
be owned by libvirt.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
Make sure ISO files have read permission while starting VM

libvirt needs to have read permission on cdrom files in order to start
the virtual machine without problems.

Otherwise, the user will get the following error:

$ sudo virsh start aaaa
error: Failed to start domain aaaa
error: internal error process exited while connecting to monitor: kvm:
-drive file=/root/Fedora-Live-Desktop-x86_64-19-1.iso: could not open disk image
/root/Fedora-Live-Desktop-x86_64-19-1.iso: Permission denied

So make sure the ISO file has read permission before starting the
virtual machine.

Signed-off-by: Aline Manera <alinefm@br.ibm.com>