lib: Remove form element `Note'

Zend already provides this.
monitoring/commands: Add 'command-form' partial

refs #6593
monitoring/lib: Add `MonitoredObjectController'

The `MonitoredObjectController' should be the base class for the host and service controller.
monitoring: Deprecate `MonitoringState' view helper
Deprecate monitoring module related methods in the `Util' view helper
monitoring/`MonitoredObject': Use `host_name' and `service_description' for filtering
monitoring/`Host': Add `fetchServices', `fetchStats' and `getStateText'
Fix `ActionController::prepareInit()' php doc
monitoring/`Service': Add `getStateText()', let `getHost()' return the host object

refs #6593
modules/commands: Fix `IcingaCommandFileCommandRenderer's `getHost()' and `getService()' calls

refs #6593
monitoring/`ServiceController': Extend `MonitoredObjectController'
monitoring: Add `HostController'
monitoring/commands: Add schedule host downtime command form

refs #6593
monitoring/commands: Add schedule host check command form

refs #6593