Bulk of updates for ironic-discoverd

* Use new configuration option from 0.2.0
* Rename units to match future ironic-discoverd RPM
* Port changes from PR #32:
  * Configure discovery parameters in answers file
  * Use configuration file instead of command-line parameters for dnsmasq
the service shouldn't be enabled until it's properly configured, otherwise it will start and fail, or have undefined behavior.
can you move the os-svc-enable down to where the os-svc-restart is in  elements/ironic-discoverd/os-refresh-config/post-configure.d/99-restart-discovery