Fixes an issue where failure notification stuck into running statuswhen timeout.LP#1996835

Fixes an issue that could be caused by a user sending a malformedhost notification missing host status. Such notification wouldblock the host from being added back from maintenance untilmanual intervention or notification expiration.LP#1960619

Fixes “Instance stopping fails randomly due to already stopped instances”.LP#1980736

Nova compute service “disable reason” is now setin case of host or process failure.It can be customised per type of failure via config.

Fixes Masakari API to properly return error codes for invalid requeststo the user instead of 500.LP#1932194