Updated Host model, added HostMonitoringSequence
Added HMS controller, views and basic tests
Minor menu and index fixes
Additional schema restrictions

* Timestamp in MonitoringSequence cannot be null
Added Source to Hosts, updated tests and views
Added monitoring_sink for hosts mon_data
Added get_hosts to Connector impls.
Added hosts to imports
Merge pull request #2 from arax/host_monitoring

Host monitoring