Add metrics from Tinkoff libvirt exporter

[Dmitry-Eremeev]

Added metrics from archived Tinkoff exporter:
libvirt_domain_block_stats_read_time_seconds_total
libvirt_domain_block_stats_write_time_seconds_total
libvirt_domain_block_stats_flush_requests_total
libvirt_domain_block_stats_flush_time_seconds_total
libvirt_domain_block_stats_capacity_bytes
libvirt_domain_memory_stats_used_percent
libvirt_domain_memory_stats_actual_balloon_bytes
libvirt_domain_memory_stats_major_fault_total
libvirt_domain_memory_stats_minor_fault_total

#22

[Knalltuete5000]

Thanks for the contribution @Dmitry-Eremeev

1. Could you be so kind to rebase your mr and adjust the logging. The common promtool library has changed the logging from go-kit/log to the new builtin library. These dependencies have been updated. For the usage you can refere to the main.go

2. Have you tested your change on a system. I assume so, since you have adjusted the readme to include the new metrics

Thank you

[Dmitry-Eremeev]

Thanks for the contribution @Dmitry-Eremeev

1. Could you be so kind to rebase your mr and adjust the logging. The common promtool library has changed the logging from go-kit/log to the new builtin library. These dependencies have been updated. For the usage you can refere to the main.go

done

2. Have you tested your change on a system. I assume so, since you have adjusted the readme to include the new metrics

it's already there

Thank you

[frittentheke]

Thanks @Dmitry-Eremeev for your contribution!