Removed InfoId interface{} alias

The InfoId type gave the illusion that InfoId was some specific type, however it is not. As an alias for interface{}, _anything_ can be used or converted to this type.
one more place InfoId was used
Merge pull request #854 from davecheney/203-state-multiwatcher-simplify

Remove InfoId interface{} alias

The InfoId type gave the illusion that InfoId was some specific type, however it is not. As an alias for interface{}, _anything_ can be used or converted to this type.