Updating to newer Golang client library for Prometheus

This is part of resolving a metric limit bug at iamseth#111

Author: neilschelly

go.mod

@@ -0,0 +1,16 @@
+module github.com/iamseth/oracledb_exporter
+
+go 1.14
+
+require (
+	github.com/BurntSushi/toml v0.3.1
+	github.com/beorn7/perks v1.0.0
+	github.com/golang/protobuf v1.3.1
+	github.com/mattn/go-oci8 v0.0.0-20160329132525-7a6ecfe0eedf
+	github.com/matttproud/golang_protobuf_extensions v1.0.1
+	github.com/prometheus/client_golang v1.0.0
+	github.com/prometheus/client_model v0.0.0-20190129233127-fd36f4220a90
+	github.com/prometheus/common v0.6.0
+	github.com/prometheus/procfs v0.0.2
+	golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a
+)

main.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 
 	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/log"
 	//Required for debugging
 	//_ "net/http/pprof"
@@ -412,7 +413,7 @@ func main() {
 	}
 	exporter := NewExporter(dsn)
 	prometheus.MustRegister(exporter)
-	http.Handle(*metricPath, prometheus.Handler())
+	http.Handle(*metricPath, promhttp.Handler())
 	http.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
 		w.Write(landingPage)
 	})