Issue #1264 : Libvirt check should only look for socket

[ravanelli]

Change is_libvirtd_up function to check libvirt socket instead of systemd

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[ravanelli]

Change is_libvirtd_up function to check socket instead of systemd

[alinefm]

@ravanelli let me know your thoughts on my comments.

[alinefm]

Thank you, @ravanelli