Rework pkg/log, add 'loglevel' and 'logdate' flags, streamline

- removes some previously added manual location strings: now handled by pkg/log depending on loglevel
- kept manual string locations on fmt print functions
- add 'notice' and 'critical' loglevels
- add 'Panic' and 'Panicf' functions to log panics
- adresses issue #26

pkg/schema/validate.go

@@ -54,7 +54,7 @@ func Validate(k Kind, r io.Reader) (err error) {
 
 	var v interface{}
 	if err := json.NewDecoder(r).Decode(&v); err != nil {
-		log.Errorf("SCHEMA/VALIDATE > Failed to decode %v", err)
+		log.Errorf("Failed to decode %v", err)
 		return err
 	}