This change updates documentation, examples and tests to support
Ironic inspection through DHCP-relay. The dnsmasq service should be
configured with more specific format set in the variable
``ironic_dnsmasq_dhcp_range``. See the dnsmasq manual page [1].

[1] https://thekelleys.org.uk/dnsmasq/docs/dnsmasq-man.html



Change-Id: I9488a72db588e31289907668f1997596a8ccdec6
Signed-off-by: Maksim Malchuk <maksim.malchuk@gmail.com>