Initial QSfera import

Server/vendor/github.com/go-kit/log/level/doc.go

@@ -0,0 +1,33 @@
+// Package level implements leveled logging on top of Go kit's log package. To
+// use the level package, create a logger as per normal in your func main, and
+// wrap it with level.NewFilter.
+//
+//    var logger log.Logger
+//    logger = log.NewLogfmtLogger(os.Stderr)
+//    logger = level.NewFilter(logger, level.AllowInfo()) // <--
+//    logger = log.With(logger, "ts", log.DefaultTimestampUTC)
+//
+// It's also possible to configure log level from a string. For instance from
+// a flag, environment variable or configuration file.
+//
+//    fs := flag.NewFlagSet("myprogram")
+//    lvl := fs.String("log", "info", "debug, info, warn, error")
+//
+//    var logger log.Logger
+//    logger = log.NewLogfmtLogger(os.Stderr)
+//    logger = level.NewFilter(logger, level.Allow(level.ParseDefault(*lvl, level.InfoValue()))) // <--
+//    logger = log.With(logger, "ts", log.DefaultTimestampUTC)
+//
+// Then, at the callsites, use one of the level.Debug, Info, Warn, or Error
+// helper methods to emit leveled log events.
+//
+//    logger.Log("foo", "bar") // as normal, no level
+//    level.Debug(logger).Log("request_id", reqID, "trace_data", trace.Get())
+//    if value > 100 {
+//        level.Error(logger).Log("value", value)
+//    }
+//
+// NewFilter allows precise control over what happens when a log event is
+// emitted without a level key, or if a squelched level is used. Check the
+// Option functions for details.
+package level