Pause job submission and observation

Fixed #128 

### Specifiication
- host has 'status' field
  - status field is either enable or disable
  - status disable means that the host does not submit and include any jobs
- update host view
  - host status is editable
  - separate 'host status' to 'job status' and 'scheduler status'
Note
- restart worker before try to change host status.