Status checking

Monit service has fields `status` and `status_hint`. If error occurs then monit sets bit in status field and resets same bit in status_hint.
I add constants and method for errors checking in status field.

Ah I get it now, thanks for explaining.

I guess I prefer the ActiveRecord way of doing things. `.valid?` doesn't let you assert against specific errors but rather only generally if there was an error. To check against specific errors, you have to check `.errors`

I suppose it's just personal preference, though.