(2.10) Minor changes regarding hotplug support

(2.10) Minor changes regarding hotplug support

* Mention restrictions in NEWS
  - RBD userspace access mode
  - In case of a downgrade instances should suffer a reboot to be migrateable
* Bypass interactive verification in NIC modifications via --force option
  - Mention it in man page
* Print "modifications take place after restart" message no matter if
  --hotplug option is passed. Change cmdlib to append hotplug status info
  (if any) to the final result printed out to the user
* Change hotplug option description

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>
Signed-off-by: Thomas Thrainer <thomasth@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>

Conflicts:
	NEWS

Signed-off-by: Dimitris Aragiorgis <dimara@grnet.gr>