Refactor PR #157 to fit the new repository format.

This didn't actually need all that much change, it fits perfectly.

Author: wrouesnel

main.go renamed to cmd/postgres_exporter/main.go

@@ -5,12 +5,14 @@ import (
 	"net/http"
 	"runtime"
 
+	"gopkg.in/alecthomas/kingpin.v2"
+
 	_ "github.com/lib/pq"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/log"
+
 	"github.com/wrouesnel/postgres_exporter/collector"
-	"gopkg.in/alecthomas/kingpin.v2"
 )
 
 // Version is set during build to the git describe version